A159585 - OEIS

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A159585

Nearest k to j such that k*(2^j-1)+1 is prime where j=A000043(n) and 2^j-1 = Mersenne-prime(n) = A000668(n). If there are two k values equidistant from j, each of which produces a prime, the larger of the two gets added to the sequence.

2, 4, 10, 4, 46, 22, 16, 46, 66, 136, 166, 124, 636, 550, 1474, 3066, 1656, 1816, 3708, 9436, 1746, 3696, 11262, 40138, 25900, 20808, 60340, 58818

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OFFSET

1,1

LINKS

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

EXAMPLE

n=6, j=A000043(6)=17, A000668(6)=131071, then k=12 or k=22 are the nearest values to j which produce primes so we take the larger of the two k values for a(6)=22.

CROSSREFS

Cf. A000043, A000668, A098556, A101416.

Sequence in context: A302349 A135445 A098556 * A130334 A375597 A320537

Adjacent sequences: A159582 A159583 A159584 * A159586 A159587 A159588

KEYWORD

hard,nonn

AUTHOR

Ray Chandler, Apr 16 2009

STATUS

approved