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Search: id:A051865
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| 0, 1, 13, 36, 70, 115, 171, 238, 316, 405, 505, 616, 738, 871, 1015, 1170, 1336, 1513, 1701, 1900, 2110, 2331, 2563, 2806, 3060, 3325, 3601, 3888, 4186, 4495, 4815, 5146, 5488, 5841, 6205, 6580, 6966, 7363, 7771, 8190, 8620, 9061, 9513
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Triskaidecagonal (or tridecagonal) numbers. [From Omar E. Pol (info(AT)polprimos.com), Dec 09 2008]
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REFERENCES
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A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, p. 189.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..1000
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FORMULA
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a(n)=n(11n-9)/2.
a(n)=11*n+a(n-1)-21 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
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EXAMPLE
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For n=2, a(2)=11*2+0-21=1; n=3, a(3)=11*3+1-21=13; n=4, a(4)=11*4+13-21=36 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
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MAPLE
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a[0]:=0:a[1]:=1:for n from 2 to 50 do a[n]:=2*a[n-1]-a[n-2]+11 od: seq(a[n], n=0..42); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 18 2008
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MATHEMATICA
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s=0; lst={s}; Do[s+=n++ +1; AppendTo[lst, s], {n, 0, 6!, 11}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 15 2008]
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CROSSREFS
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Cf. A000217, A051624, A051866.
Sequence in context: A034119 A054285 A101103 this_sequence A081928 A034129 A118361
Adjacent sequences: A051862 A051863 A051864 this_sequence A051866 A051867 A051868
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KEYWORD
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nonn,new
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Dec 15 1999
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