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Search: id:A006137
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| 1, 6, 20, 43, 75, 116, 166, 225, 293, 370, 456, 551, 655, 768, 890, 1021, 1161, 1310, 1468, 1635, 1811, 1996, 2190, 2393, 2605, 2826, 3056, 3295, 3543, 3800, 4066, 4341, 4625, 4918, 5220, 5531, 5851, 6180
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=3*a(n-1)-3*a(n-2)+a(n-3), with a(0)=1, a(1)=6 and a(2)=20. [From Paolo P. Lava (ppl(AT)spl.at), Jul 17 2009]
a(n)=9*n+a(n-1)-13 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 10 2009]
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EXAMPLE
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For n=2, a(2)=9*2+1-13=6; n=3, a(3)=9*3+6-13=20; n=4, a(4)=9*4+20-13=43 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 10 2009]
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MATHEMATICA
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s = 1; lst = {s}; Do[s += n + 4; AppendTo[lst, s], {n, 1, 350, 9}]; lst [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 11 2009]
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CROSSREFS
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Sequence in context: A094274 A094279 A093913 this_sequence A048969 A005564 A011928
Adjacent sequences: A006134 A006135 A006136 this_sequence A006138 A006139 A006140
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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