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Search: id:A080859
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| A080859 |
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Generalized polygonal numbers. |
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+0
2
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| 1, 11, 33, 67, 113, 171, 241, 323, 417, 523, 641, 771, 913, 1067, 1233, 1411, 1601, 1803, 2017, 2243, 2481, 2731, 2993, 3267, 3553, 3851, 4161, 4483, 4817, 5163, 5521, 5891, 6273, 6667, 7073, 7491, 7921, 8363, 8817, 9283, 9761, 10251, 10753, 11267
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Column T(n,4) of A080853
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FORMULA
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a(n) = C(4, 0)+C(4, 1)n+C(4, 2)n^2 = 6n^2+4n+1 G.f. (C(3, 0)+(C(5, 2)-2)*x+C(3, 2)*x^2)/(1-x)^3 = (1+8x+3x^2)/(1-x)^3
a(n)=12*n+a(n-1)-14 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 15 2009]
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EXAMPLE
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For n=2, a(2)=12*2+1-14=11; n=3, a(3)=12*3+11-14=33; n=4, a(4)=12*4+33-14=67 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 15 2009]
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CROSSREFS
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Sequence in context: A061833 A132285 A152740 this_sequence A063036 A163673 A027025
Adjacent sequences: A080856 A080857 A080858 this_sequence A080860 A080861 A080862
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KEYWORD
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easy,nonn,new
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Feb 23 2003
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