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A057225
Numbers k such that (Product of first k Mersenne prime exponents) - 1 is prime.
1
2, 3, 5, 9, 13, 27
OFFSET
1,1
COMMENTS
a(7) > 48, if it exists. - Amiram Eldar, Oct 19 2024
MATHEMATICA
Position[FoldList[Times, MersennePrimeExponent[Range[30]]]-1, _?PrimeQ]//Flatten (* Harvey P. Dale, Oct 01 2023 *)
PROG
(PARI) lista(v) = {for (n=1, #v, if (isprime(prod(k=1, n, v[k]) - 1), print1(n, ", ")); ); } \\ with v=A000043. Michel Marcus, Jan 07 2014
CROSSREFS
Sequence in context: A175125 A171925 A186946 * A309289 A220315 A070819
KEYWORD
nonn,more,changed
AUTHOR
G. L. Honaker, Jr., Sep 18 2000
STATUS
approved