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Search: id:A139485
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| A139485 |
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a(1)=1. For m>=0 and 1<=k<=2^m, a(2^m +k) = a(k) + sum{j=1 to 2^m) a(j). |
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+0
2
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| 1, 2, 4, 5, 13, 14, 16, 17, 73, 74, 76, 77, 85, 86, 88, 89, 721, 722, 724, 725, 733, 734, 736, 737, 793, 794, 796, 797, 805, 806, 808, 809, 12961, 12962, 12964, 12965, 12973, 12974, 12976, 12977, 13033, 13034, 13036, 13037, 13045, 13046, 13048, 13049
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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A139486(n) = sum{j=1 to 2^n) a(j).
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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FORMULA
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For odd n, a(n) = SUM[j=0..k] b(j) * A139486(j), where n = SUM[j=0..k] b(j) * 2^j is the binary representation of n. For even n, a(n) = a(n-1) + 1. [From Max Alekseyev (maxale(AT)gmail.com), Oct 24 2008]
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PROGRAM
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(PARI) { A139485(n) = local(b); if(n%2==0, return(a(n-1)+1)); b=Vecrev(binary(n)); sum(j=1, #b, b[j]*prod(i=0, j-2, 2^i+2)) } [From Max Alekseyev (maxale(AT)gmail.com), Oct 24 2008]
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CROSSREFS
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Cf. A139486.
Sequence in context: A050599 A102932 A128457 this_sequence A079407 A078652 A102992
Adjacent sequences: A139482 A139483 A139484 this_sequence A139486 A139487 A139488
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Apr 23 2008
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EXTENSIONS
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Formula and more term from Max Alekseyev (maxale(AT)gmail.com), Oct 24 2008
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