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Search: id:A080355
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| A080355 |
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a(1)=1; for n>1, a(n) = a(n-1) + 2^(j-1), where j is position of n-th 1 in A080339. |
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+0
18
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| 1, 3, 7, 23, 87, 1111, 5207, 70743, 332887, 4527191, 272962647, 1346704471, 70066181207, 1169577808983, 5567624320087, 75936368497751, 4579535995868247, 292809912147579991, 1445731416754426967
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Or, take an initial segment of A080339, stopping at the n-th 1, reverse and interpret as a binary number. E.g. to get the 4-th term: 11101 -> 10111 = 23, so a(4) = 23.
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FORMULA
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a(n) = 1 + Sum_{k=1..n-1} 2^(prime(k)-1).
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CROSSREFS
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Cf. A076793.
Sequence in context: A136508 A099152 A113860 this_sequence A100964 A080077 A096318
Adjacent sequences: A080352 A080353 A080354 this_sequence A080356 A080357 A080358
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), based on information supplied by Artur Jasinski (grafix(AT)csl.pl), Mar 21 2003
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 26 2003
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