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Search: id:A098923
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| 0, 1, 33, 96, 190, 315, 471, 658, 876, 1125, 1405, 1716, 2058, 2431, 2835, 3270, 3736, 4233, 4761, 5320, 5910, 6531, 7183, 7866, 8580, 9325, 10101, 10908, 11746, 12615, 13515, 14446, 15408, 16401, 17425, 18480, 19566, 20683, 21831, 23010
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OFFSET
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0,3
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COMMENT
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Similar to 21-gonal and 15-gonal numbers.
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FORMULA
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a(n)=31*n+a(n-1)-61 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 15 2009]
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EXAMPLE
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If n=10, 10*(31*10 - 29)/2 = 1405
For n=2, a(2)=31*2+0-61=1; n=3, a(3)=31*3+1-61=33; n=4, a(4)=31*4+33-61=96 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 15 2009]
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MATHEMATICA
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Table[n(31n - 29)/2, {n, 0, 40}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 15 2006
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CROSSREFS
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Cf. A051873, A051867.
Sequence in context: A114069 A165378 A098938 this_sequence A044220 A044601 A098441
Adjacent sequences: A098920 A098921 A098922 this_sequence A098924 A098925 A098926
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KEYWORD
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nonn,new
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Oct 18 2004
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 15 2006
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