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A185372
Least positive integer which, when added to each of the first n Mersenne primes, yields all primes.
0
2, 4, 10, 10, 40, 40, 100, 32296, 65836, 214510186, 413879926, 1772668756
OFFSET
1,1
COMMENTS
J. L. Selfridge proved that a(8) > 100.
MATHEMATICA
lst = {}; p = 18; Do[p = Prime[n]; If[PrimeQ[2^p - 1], AppendTo[lst, p]], {n, p}]; Table[k = 1; While[i = 1; While[i <= n && PrimeQ[2^lst[[i]] + k], i++]; i <= n, k++]; k + 1, {n, Count[lst, _Integer]}]
CROSSREFS
Cf. A000043.
Sequence in context: A092945 A320150 A056376 * A186757 A184876 A243622
KEYWORD
hard,more,nonn
AUTHOR
STATUS
approved