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Search: id:A057569
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| A057569 |
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Numbers of the form n*(5n+-1)/2. |
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+0
9
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| 0, 2, 3, 9, 11, 21, 24, 38, 42, 60, 65, 87, 93, 119, 126, 156, 164, 198, 207, 245, 255, 297, 308, 354, 366, 416, 429, 483, 497, 555, 570, 632, 648, 714, 731, 801, 819, 893, 912, 990, 1010, 1092, 1113, 1199, 1221, 1311, 1334, 1428, 1452, 1550
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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A005475 UNION A005476. o.g.f.: x(2x^2+x+2)/[(1-x)^3*(1+x)^2]. a(n)=A132356(n)/4. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 07 2008
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MATHEMATICA
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#1. lst={}; s=0; Do[s+=n/5; If[Floor[s]==s, AppendTo[lst, s]], {n, 0, 7!}]; lst #2. lst={}; Do[AppendTo[lst, n*(5*n-1)/2]; AppendTo[lst, n*(5*n+1)/2], {n, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 06 2009]
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CROSSREFS
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Cf. A074378, A001318, A057570, A154260 [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 06 2009]
Sequence in context: A111319 A109658 A110350 this_sequence A049618 A057292 A098016
Adjacent sequences: A057566 A057567 A057568 this_sequence A057570 A057571 A057572
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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), Oct 04 2000
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