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Search: id:A084566
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| A084566 |
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a(0)=1, a(2n) = 2a(2n-1)+a(n), a(2n+1) = 2a(2n)+2a(n). |
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+0
1
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| 1, 4, 12, 32, 76, 176, 384, 832, 1740, 3632, 7440, 15232, 30848, 62464, 125760, 253184, 508108, 1019696, 2043024, 4093312, 8194064, 16403008, 32821248, 65672960, 131376768, 262815232, 525692928, 1051510784, 2103147328
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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a(n) ~ 2^(n+e) with e = 2.9701632052178...
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FORMULA
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G.f. prod(k>=0, (1+2x^2^k)/(1-2x^2^k)).
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PROGRAM
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(PARI) a(n)=if(n<1, n<1, if(n%2==0, 2*a(n-1)+a(n/2), 2*a(n-1)+2*a((n-1)/2)))
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CROSSREFS
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Cf. A018819.
Sequence in context: A138517 A001934 A004403 this_sequence A079769 A107035 A118885
Adjacent sequences: A084563 A084564 A084565 this_sequence A084567 A084568 A084569
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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), Jun 28 2003
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