A201457 Least k such that (7^n + k)*7^n - 1 is a prime number.
5, 11, 1, 11, 23, 29, 17, 31, 13, 37, 61, 11, 35, 149, 17, 151, 17, 17, 17, 13, 59, 17, 73, 47, 43, 13, 113, 77, 119, 97, 125, 83, 13, 421, 103, 103, 77, 23, 23, 79, 5, 107, 7, 37, 59, 113, 11, 1, 169, 887, 137, 41, 113, 71, 277, 413, 97, 91, 227, 337, 97, 353, 233, 953, 5, 139, 77, 473, 73, 167, 275, 67, 49, 97, 365, 73, 223, 241, 115
Offset: 1
Keywords
Programs
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Mathematica
Table[k = 0; While[!PrimeQ[(7^n + k)*7^n - 1], k++]; k, {n, 85}]