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%I #19 Oct 19 2024 08:34:46
%S 2,3,5,9,13,27
%N Numbers k such that (Product of first k Mersenne prime exponents) - 1 is prime.
%C a(7) > 48, if it exists. - _Amiram Eldar_, Oct 19 2024
%t Position[FoldList[Times,MersennePrimeExponent[Range[30]]]-1,_?PrimeQ]//Flatten (* _Harvey P. Dale_, Oct 01 2023 *)
%o (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
%Y Cf. A000043, A057224.
%K nonn,more
%O 1,1
%A _G. L. Honaker, Jr._, Sep 18 2000