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A098818 Smallest k such that k*Mersenne_prime(n)^2 -1 (or k*A000668(n)^2 -1) is prime. 0
2, 2, 8, 2, 12, 2, 2, 98, 38, 122, 126, 678, 440, 1040, 776, 1398, 2714, 3362, 650, 8910, 22010, 11172, 1422, 5274, 33944, 4508, 12614, 202298, 275466 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

2*((2^2-1)^2)-1=17 prime so a(1)=2.

CROSSREFS

Cf. A000668

Sequence in context: A174354 A011147 A273168 * A092694 A098984 A088560

Adjacent sequences:  A098815 A098816 A098817 * A098819 A098820 A098821

KEYWORD

more,nonn

AUTHOR

Pierre CAMI, Oct 08 2004

EXTENSIONS

a(19)-a(22) from Donovan Johnson, Mar 23 2008

a(23)-a(29) from Pierre CAMI, Feb 15 2014

STATUS

approved

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Last modified April 25 13:31 EDT 2019. Contains 322461 sequences. (Running on oeis4.)