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Search: id:A125180
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| A125180 |
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a(n)=2a(n-1)+p(n)-p(n-1), a(1)=2, where p(n) denotes the n-th prime. |
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+0
2
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| 2, 5, 12, 26, 56, 114, 232, 466, 936, 1878, 3758, 7522, 15048, 30098, 60200, 120406, 240818, 481638, 963282, 1926568, 3853138, 7706282, 15412568, 30825142, 61650292, 123300588, 246601178, 493202360, 986404722, 1972809448, 3945618910
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Row sums of A125179. lim(a(n)/a(n-1), n->infinity)=2.
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FORMULA
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a(n)=p(n)+Sum(2^(n-j-1)*p(j),j=1..n-1), where p(k) denotes the k-th prime.
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EXAMPLE
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a(4)=26 because 4p(1)+2p(2)+p(3)+p(4)=8+6+5+7=26.
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MAPLE
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a[1]:=2: for n from 2 to 35 do a[n]:=2*a[n-1]+ithprime(n)-ithprime(n-1) od: seq(a[n], n=1..35);
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CROSSREFS
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Cf. A125179.
Sequence in context: A026622 A026688 A116726 this_sequence A073778 A033490 A116716
Adjacent sequences: A125177 A125178 A125179 this_sequence A125181 A125182 A125183
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KEYWORD
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nonn
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Nov 22 2006
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Dec 02 2006
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