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A101416 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. 1
2, 2, 2, 6, 20, 14, 32, 90, 72, 80, 230, 80, 560, 740, 1542, 1782, 450, 828, 2562, 3936, 12474, 9288, 10224, 16022, 11088, 31034, 53972, 92372 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

n=7, j=A000043(7)=19, A000668(7)=524287, then k=6 or k=32 are the nearest values to j which produce primes so we take the larger of the two k values for a(7)=32.

CROSSREFS

Cf. A000043, A000668, A098555, A159585.

Sequence in context: A025248 A213170 A321741 * A098920 A270557 A129365

Adjacent sequences:  A101413 A101414 A101415 * A101417 A101418 A101419

KEYWORD

hard,nonn

AUTHOR

Pierre CAMI, Jan 16 2005

EXTENSIONS

a(5)=20, a(20)=3936 corrected, other terms verified, a(27)-a(28) extended by Ray Chandler, Apr 16 2009

STATUS

approved

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Last modified July 21 04:40 EDT 2019. Contains 325189 sequences. (Running on oeis4.)