A201459 Least k such that (7^n - k)*7^n - 1 is a prime number.

1, 1, 5, 7, 7, 11, 5, 29, 13, 29, 5, 1, 77, 1, 13, 101, 65, 77, 175, 29, 77, 121, 49, 23, 41, 31, 613, 101, 13, 37, 127, 47, 197, 31, 107, 97, 275, 17, 619, 47, 7, 199, 85, 31, 47, 17, 97, 253, 17, 37, 5, 103, 215, 119, 335, 257, 277, 121, 313, 89, 157, 187, 25, 7, 571, 11, 197, 53, 13, 101, 49, 199, 67, 389, 109, 13, 25, 41, 337, 647, 77

Offset

1,3

Links

Table of n, a(n) for n=1..81.

Mathematica

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

Crossrefs

Cf. A191620, A200922, A201132.

Sequence in context: A137755 A258316 A244621 * A053672 A087525 A078496

Adjacent sequences: A201456 A201457 A201458 * A201460 A201461 A201462

Keyword

nonn

Author

Michel Lagneau, Dec 01 2011

Status

approved