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A201459
Least k such that (7^n - k)*7^n - 1 is a prime number.
0
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
MATHEMATICA
Table[k = 0; While[!PrimeQ[(7^n - k)*7^n - 1], k++]; k, {n, 85}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Dec 01 2011
STATUS
approved