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Search: id:A154260
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| A154260 |
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Integers of the form : n*(4*n-+1)/2. |
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+0
4
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| 0, 7, 9, 30, 34, 69, 75, 124, 132, 195, 205, 282, 294, 385, 399, 504, 520, 639, 657, 790, 810, 957, 979, 1140, 1164, 1339, 1365, 1554, 1582, 1785, 1815, 2032, 2064, 2295, 2329, 2574, 2610, 2869, 2907, 3180, 3220, 3507, 3549, 3850, 3894, 4209, 4255, 4584
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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A139274 UNION A139275. Conjecture: a(n)=a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5). G.f.: x^2*(7+2x+7x^2)/((1+x)^2*(1-x)^3). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 07 2009]
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MATHEMATICA
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#1. lst={}; s=0; Do[s+=n/4; If[Floor[s]==s, AppendTo[lst, s]], {n, 0, 7!}]; lst #2. lst={}; Do[a=n*(4*n-1)/2; If[Floor[a]==a, AppendTo[lst, a]]; a=n*(4*n+1)/2; If[Floor[a]==a, AppendTo[lst, a]], {n, 6!}]; lst
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CROSSREFS
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Cf. A001318, A074378, A057569, A057570
Sequence in context: A113124 A030404 A066930 this_sequence A085903 A147248 A147186
Adjacent sequences: A154257 A154258 A154259 this_sequence A154261 A154262 A154263
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 06 2009
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