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A143384 Least a(n) such that M(n)*(M(n)+a(n))-1 is prime with M(i)=i-th Mersenne prime. 2
1, 5, 1, 5, 11, 11, 17, 19, 23, 97, 127, 145, 167, 269, 767, 479, 3307, 1453, 18007, 2357, 599, 17669, 5527, 3191, 3251, 70249, 147773, 39637 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All primes certified using PFGW from Primeform group.

M(n) = 2^A000043(n)-1. - Jens Kruse Andersen, Jul 30 2014

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

(2^2-1)*(2^2-1+1)-1=11 prime 2^2-1=M(1) so a(1)=1

(2^3-1)*(2^3-1+1)-1=55 composite

(2^3-1)*(2^3-1+3)-1=69 composite

(2^3-1)*(2^3-1+5)-1=83 prime 2^3-1=M(2) so a(2)=5

CROSSREFS

Cf. A000043 (Mersenne prime exponents), A143385.

Sequence in context: A255166 A131113 A139426 * A046611 A145825 A101692

Adjacent sequences:  A143381 A143382 A143383 * A143385 A143386 A143387

KEYWORD

hard,more,nonn

AUTHOR

Pierre CAMI, Aug 11 2008

EXTENSIONS

Missing terms 2357 and 599 inserted by Jens Kruse Andersen, Jul 30 2014

STATUS

approved

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Last modified December 8 00:04 EST 2021. Contains 349590 sequences. (Running on oeis4.)