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A156893 Primes of the form 1 + 2 * Product_{i=1..k} (2^i-1). 0
3, 7, 43, 631, 19531, 1230391, 39846180151, 42638416803867688651, 1430183959005766573513154251 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form 2*A005329(k)+1.

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

For n=4, 2*(2^1 - 1)*(2^2 - 1)*(2^3 -1)*(2^4 - 1) + 1 = 2*1*3*7*15 + 1 = 631

CROSSREFS

Sequence in context: A181729 A162455 A143684 * A050639 A280717 A100837

Adjacent sequences:  A156890 A156891 A156892 * A156894 A156895 A156896

KEYWORD

nonn

AUTHOR

J. M. Bergot, Feb 17 2009

EXTENSIONS

Definition and terms corrected by R. J. Mathar, Jul 10 2011

STATUS

approved

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Last modified May 19 18:35 EDT 2022. Contains 353847 sequences. (Running on oeis4.)