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A119529 Numbers k such that Sum_{j=1..k-1} j*2^(j-1) is prime. 4
3, 4, 8, 28, 52, 56, 82, 1472, 1484, 8669 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

MATHEMATICA

s = 0; Do[s += (x-1)*2^(x-1)/2; If[PrimeQ[s], Print[x]], {x, 10^4}] (* Ryan Propper, Jan 01 2007 *)

CROSSREFS

Cf. A000523.

Sequence in context: A217248 A168382 A155701 * A180629 A258372 A096847

Adjacent sequences:  A119526 A119527 A119528 * A119530 A119531 A119532

KEYWORD

more,nonn

AUTHOR

Jorge Coveiro, Jul 27 2006

EXTENSIONS

One more term from Ryan Propper, Jan 01 2007

Name simplified by Jon E. Schoenfield, Sep 23 2018

STATUS

approved

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Last modified January 21 11:08 EST 2020. Contains 331105 sequences. (Running on oeis4.)