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Search: id:A086769
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| A086769 |
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a(n) = sum{2^(b(i)-1): 1<=i<=n}, where b(n) is the differences between consecutive primes. |
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+0
1
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| 1, 3, 5, 13, 15, 23, 25, 33, 65, 67, 99, 107, 109, 117, 149, 181, 183, 215, 223, 225, 257, 265, 297, 425, 433, 435, 443, 445, 453, 8645, 8653, 8685, 8687, 9199, 9201, 9233, 9265, 9273, 9305, 9337, 9339, 9851, 9853, 9861, 9863, 11911, 13959, 13967, 13969
(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) = a(n-1)+2^(p(n+1)-p(n)-1).
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EXAMPLE
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2^(3-2)/2=1, so a(1)=1. 2^(5-3)/2=2, so a(2)=1+2=3.
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PROGRAM
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(Matlab) P = primes(500); l = length(P); S = P(2:l) - P(1:(l - 1)); A = cumsum(2.^(S-1))
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CROSSREFS
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Cf. A001223.
Sequence in context: A099791 A028268 A137162 this_sequence A018753 A073217 A063484
Adjacent sequences: A086766 A086767 A086768 this_sequence A086770 A086771 A086772
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KEYWORD
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nonn,easy
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AUTHOR
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David G. Williams (davwill24(AT)aol.com), Aug 02 2003
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EXTENSIONS
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Edited by David Wasserman (wasserma(AT)spawar.navy.mil), Aug 28 2003
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