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Search: id:A091311
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| 0, 1, 4, 5, 14, 15, 18, 19, 46, 47, 50, 51, 60, 61, 64, 65, 146, 147, 150, 151, 160, 161, 164, 165, 192, 193, 196, 197, 206, 207, 210, 211, 454, 455, 458, 459, 468, 469, 472, 473, 500, 501, 504, 505, 514, 515, 518, 519, 600, 601, 604, 605, 614, 615, 618, 619
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OFFSET
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0,3
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FORMULA
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Recurrence: a(2n) = 3a(n) + n, a(2n+1) = 3a(n) + n + 1.
G.f.: 1/(1-x) * sum(k>=0, 3^k*t/(1-t^2), t=x^2^k).
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PROGRAM
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(PARI) a(n)=sum(k=1, n, 3^valuation(n, 2))
(PARI) a(n)=if(n<1, 0, if(n%2==0, 3*a(n/2)+n/2, 3*a((n-1)/2)+(n+1)/2))
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CROSSREFS
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First differences are A061393(n)-1.
Equals 2*A005836(n) - n.
Sequence in context: A102981 A029663 A082312 this_sequence A008540 A000867 A049770
Adjacent sequences: A091308 A091309 A091310 this_sequence A091312 A091313 A091314
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KEYWORD
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nonn,easy
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AUTHOR
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Ralf Stephan (ralf(AT)ark.in-berlin.de), Feb 24 2004
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