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A121371 Least number k such that (k*M(n))^2 + k*M(n) - 1 and (k*M(n))^2 + k*M(n) + 1 are twin primes with M(i)=i-th Mersenne prime. 1
1, 3, 5, 8, 99, 275, 278, 409, 96, 1538, 1253, 15858, 189168, 119552, 221444, 1047122, 3571449 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

M(2)=2^3-1=7

7^2+7-1=55 composite

(2*7)^2+2*7-1=209 composite

(3*7)^2+3*7-1=461 prime, 461 and 463 are twin primes so k(2)=3

CROSSREFS

Cf. A121370.

Sequence in context: A174529 A174442 A109342 * A067094 A272235 A058642

Adjacent sequences:  A121368 A121369 A121370 * A121372 A121373 A121374

KEYWORD

hard,more,nonn

AUTHOR

Pierre CAMI, Jul 24 2006

STATUS

approved

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Last modified December 10 04:09 EST 2016. Contains 278993 sequences.