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Search: id:A091519
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| A091519 |
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G.f.: sum(k>=0, 2^k*t*(1+t)/(1-t)^3, t=x^2^k). |
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+0
2
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| 1, 6, 9, 28, 25, 54, 49, 120, 81, 150, 121, 252, 169, 294, 225, 496, 289, 486, 361, 700, 441, 726, 529, 1080, 625, 1014, 729, 1372, 841, 1350, 961, 2016, 1089, 1734, 1225, 2268, 1369, 2166, 1521, 3000, 1681, 2646, 1849, 3388, 2025, 3174, 2209
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n) = 2n^2 - n*A000265(n) = n*A000265(n)*A038712(n).
Recurrence: a(0) = 0, a(2n) = 2a(n) + (2n)^2, a(2n+1) = (2n+1)^2.
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PROGRAM
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(PARI) a(n)=2*n*n-n*n/2^valuation(n, 2)
(PARI) a(n)=if(n<1, 0, if(n%2==0, 2*a(n/2)+n^2, n^2))
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CROSSREFS
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Sequence in context: A007414 A025493 A054871 this_sequence A086491 A147415 A105866
Adjacent sequences: A091516 A091517 A091518 this_sequence A091520 A091521 A091522
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KEYWORD
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nonn,easy
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AUTHOR
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R. Stephan (ralf(AT)ark.in-berlin.de), Jan 18 2004
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