login
A098570
Least k such that Mersenne-prime(n)*prime(k)# - 1 is prime, where prime(k)# is the k-th primorial.
1
1, 1, 1, 2, 1, 3, 1, 10, 9, 7, 9, 7, 36, 105, 375, 120, 280, 226, 1215, 263, 2098, 310, 2330
OFFSET
1,4
MATHEMATICA
f[p_] := Module[{m = 1, k = 2, q = 2}, While[!PrimeQ[k*p - 1], q = NextPrime[q]; k *= q; m++]; m]; f /@ (2^MersennePrimeExponent[Range[15]] - 1) (* Amiram Eldar, Jul 25 2021 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Pierre CAMI, Sep 16 2004
EXTENSIONS
a(21)-a(23) from Amiram Eldar, Jul 25 2021
STATUS
approved