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A201460 Least k such that (7^n - k)*7^n + 1 is a prime number. 0
1, 15, 1, 19, 51, 1, 49, 1, 1, 15, 51, 9, 21, 211, 79, 21, 7, 31, 129, 105, 87, 21, 21, 13, 7, 109, 57, 55, 159, 75, 231, 73, 33, 19, 57, 75, 3, 49, 207, 93, 463, 15, 141, 421, 151, 177, 237, 1, 99, 49, 129, 211, 79, 697, 49, 13, 237, 169, 439, 181, 201, 109, 159, 229, 271, 15, 31, 559, 57, 127, 183, 595, 43, 237, 3, 69, 463, 387, 141 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..79.

MATHEMATICA

Table[k = 0; While[!PrimeQ[(7^n - k)*7^n + 1], k++]; k, {n, 85}]

CROSSREFS

Cf. A191619, A200923, A201131.

Sequence in context: A317835 A225762 A040238 * A040239 A126141 A131514

Adjacent sequences:  A201457 A201458 A201459 * A201461 A201462 A201463

KEYWORD

nonn

AUTHOR

Michel Lagneau, Dec 01 2011

STATUS

approved

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Last modified April 18 14:54 EDT 2019. Contains 322209 sequences. (Running on oeis4.)