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A125180 a(n)=2a(n-1)+p(n)-p(n-1), a(1)=2, where p(n) denotes the n-th prime. 1
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; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row sums of A125179. lim(a(n)/a(n-1), n->infinity)=2.

LINKS

Table of n, a(n) for n=1..31.

FORMULA

a(n)=p(n)+Sum(2^(n-j-1)*p(j),j=1..n-1), where p(k) denotes the k-th prime.

EXAMPLE

a(4)=26 because 4p(1)+2p(2)+p(3)+p(4)=8+6+5+7=26.

MAPLE

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);

CROSSREFS

Cf. A125179.

Sequence in context: A026688 A116726 A228078 * A073778 A033490 A221950

Adjacent sequences:  A125177 A125178 A125179 * A125181 A125182 A125183

KEYWORD

nonn

AUTHOR

Gary W. Adamson, Nov 22 2006

EXTENSIONS

Edited by N. J. A. Sloane, Dec 02 2006

STATUS

approved

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Last modified October 17 07:05 EDT 2018. Contains 316276 sequences. (Running on oeis4.)