Mathematica'nin bunun icin IntegerPartitions[] fonksiyonu var. n=3,4,...,500 icin hesap 1 saniye falan suruyor.
Table[{n, Length@IntegerPartitions[n, {3}]}, {n, 3, 500}]
{3,1}{4,1}{5,2}{6,3}{7,4}{8,5}{9,7}{10,8}{11,10}{12,12}{13,14}{14,16}{15,19}{16,21}{17,24}{18,27}{19,30}{20,33}{21,37}{22,40}{23,44}{24,48}{25,52}{26,56}{27,61}{28,65}{29,70}{30,75}{31,80}{32,85}{33,91}{34,96}{35,102}{36,108}{37,114}{38,120}{39,127}{40,133}{41,140}{42,147}{43,154}{44,161}{45,169}{46,176}{47,184}{48,192}{49,200}{50,208}{51,217}{52,225}{53,234}{54,243}{55,252}{56,261}{57,271}{58,280}{59,290}{60,300}{61,310}{62,320}{63,331}{64,341}{65,352}{66,363}{67,374}{68,385}{69,397}{70,408}{71,420}{72,432}{73,444}{74,456}{75,469}{76,481}{77,494}{78,507}{79,520}{80,533}{81,547}{82,560}{83,574}{84,588}{85,602}{86,616}{87,631}{88,645}{89,660}{90,675}{91,690}{92,705}{93,721}{94,736}{95,752}{96,768}{97,784}{98,800}{99,817}{100,833}{101,850}{102,867}{103,884}{104,901}{105,919}{106,936}{107,954}{108,972}{109,990}{110,1008}{111,1027}{112,1045}{113,1064}{114,1083}{115,1102}{116,1121}{117,1141}{118,1160}{119,1180}{120,1200}{121,1220}{122,1240}{123,1261}{124,1281}{125,1302}{126,1323}{127,1344}{128,1365}{129,1387}{130,1408}{131,1430}{132,1452}{133,1474}{134,1496}{135,1519}{136,1541}{137,1564}{138,1587}{139,1610}{140,1633}{141,1657}{142,1680}{143,1704}{144,1728}{145,1752}{146,1776}{147,1801}{148,1825}{149,1850}{150,1875}{151,1900}{152,1925}{153,1951}{154,1976}{155,2002}{156,2028}{157,2054}{158,2080}{159,2107}{160,2133}{161,2160}{162,2187}{163,2214}{164,2241}{165,2269}{166,2296}{167,2324}{168,2352}{169,2380}{170,2408}{171,2437}{172,2465}{173,2494}{174,2523}{175,2552}{176,2581}{177,2611}{178,2640}{179,2670}{180,2700}{181,2730}{182,2760}{183,2791}{184,2821}{185,2852}{186,2883}{187,2914}{188,2945}{189,2977}{190,3008}{191,3040}{192,3072}{193,3104}{194,3136}{195,3169}{196,3201}{197,3234}{198,3267}{199,3300}{200,3333}{201,3367}{202,3400}{203,3434}{204,3468}{205,3502}{206,3536}{207,3571}{208,3605}{209,3640}{210,3675}{211,3710}{212,3745}{213,3781}{214,3816}{215,3852}{216,3888}{217,3924}{218,3960}{219,3997}{220,4033}{221,4070}{222,4107}{223,4144}{224,4181}{225,4219}{226,4256}{227,4294}{228,4332}{229,4370}{230,4408}{231,4447}{232,4485}{233,4524}{234,4563}{235,4602}{236,4641}{237,4681}{238,4720}{239,4760}{240,4800}{241,4840}{242,4880}{243,4921}{244,4961}{245,5002}{246,5043}{247,5084}{248,5125}{249,5167}{250,5208}{251,5250}{252,5292}{253,5334}{254,5376}{255,5419}{256,5461}{257,5504}{258,5547}{259,5590}{260,5633}{261,5677}{262,5720}{263,5764}{264,5808}{265,5852}{266,5896}{267,5941}{268,5985}{269,6030}{270,6075}{271,6120}{272,6165}{273,6211}{274,6256}{275,6302}{276,6348}{277,6394}{278,6440}{279,6487}{280,6533}{281,6580}{282,6627}{283,6674}{284,6721}{285,6769}{286,6816}{287,6864}{288,6912}{289,6960}{290,7008}{291,7057}{292,7105}{293,7154}{294,7203}{295,7252}{296,7301}{297,7351}{298,7400}{299,7450}{300,7500}{301,7550}{302,7600}{303,7651}{304,7701}{305,7752}{306,7803}{307,7854}{308,7905}{309,7957}{310,8008}{311,8060}{312,8112}{313,8164}{314,8216}{315,8269}{316,8321}{317,8374}{318,8427}{319,8480}{320,8533}{321,8587}{322,8640}{323,8694}{324,8748}{325,8802}{326,8856}{327,8911}{328,8965}{329,9020}{330,9075}{331,9130}{332,9185}{333,9241}{334,9296}{335,9352}{336,9408}{337,9464}{338,9520}{339,9577}{340,9633}{341,9690}{342,9747}{343,9804}{344,9861}{345,9919}{346,9976}{347,10034}{348,10092}{349,10150}{350,10208}{351,10267}{352,10325}{353,10384}{354,10443}{355,10502}{356,10561}{357,10621}{358,10680}{359,10740}{360,10800}{361,10860}{362,10920}{363,10981}{364,11041}{365,11102}{366,11163}{367,11224}{368,11285}{369,11347}{370,11408}{371,11470}{372,11532}{373,11594}{374,11656}{375,11719}{376,11781}{377,11844}{378,11907}{379,11970}{380,12033}{381,12097}{382,12160}{383,12224}{384,12288}{385,12352}{386,12416}{387,12481}{388,12545}{389,12610}{390,12675}{391,12740}{392,12805}{393,12871}{394,12936}{395,13002}{396,13068}{397,13134}{398,13200}{399,13267}{400,13333}{401,13400}{402,13467}{403,13534}{404,13601}{405,13669}{406,13736}{407,13804}{408,13872}{409,13940}{410,14008}{411,14077}{412,14145}{413,14214}{414,14283}{415,14352}{416,14421}{417,14491}{418,14560}{419,14630}{420,14700}{421,14770}{422,14840}{423,14911}{424,14981}{425,15052}{426,15123}{427,15194}{428,15265}{429,15337}{430,15408}{431,15480}{432,15552}{433,15624}{434,15696}{435,15769}{436,15841}{437,15914}{438,15987}{439,16060}{440,16133}{441,16207}{442,16280}{443,16354}{444,16428}{445,16502}{446,16576}{447,16651}{448,16725}{449,16800}{450,16875}{451,16950}{452,17025}{453,17101}{454,17176}{455,17252}{456,17328}{457,17404}{458,17480}{459,17557}{460,17633}{461,17710}{462,17787}{463,17864}{464,17941}{465,18019}{466,18096}{467,18174}{468,18252}{469,18330}{470,18408}{471,18487}{472,18565}{473,18644}{474,18723}{475,18802}{476,18881}{477,18961}{478,19040}{479,19120}{480,19200}{481,19280}{482,19360}{483,19441}{484,19521}{485,19602}{486,19683}{487,19764}{488,19845}{489,19927}{490,20008}{491,20090}{492,20172}{493,20254}{494,20336}{495,20419}{496,20501}{497,20584}{498,20667}{499,20750}{500,20833}