A201460 Least k such that (7^n - k)*7^n + 1 is a prime number.

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

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: A225762 A375940 A040238 * A381527 A040239 A126141

Adjacent sequences: A201457 A201458 A201459 * A201461 A201462 A201463

Keyword

nonn

Author

Michel Lagneau, Dec 01 2011

Status

approved