1,1

Corresponding smallest primes q such that (q^p-1)/(q-1) is prime, where p = Prime[n], are listed in A123487[n] = {2,2,2,2,5,2,2,2,113,151,2,61,53,89,5,307,19,2,491,...}. a(n) coincides with A084732[n] when A066180[n] is prime or 0.

a(n) = (A123487[n]^Prime[n] - 1) / (A123487[n] - 1).

Cf. A123487, A066180, A084732.

Sequence in context: A000668 A136007 A084732 this_sequence A121620 A042271 A000644

Adjacent sequences: A123485 A123486 A123487 this_sequence A123489 A123490 A123491

nonn

Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 30 2006