1,1

a(2)=251 is the only prime found for n up to 10000 using The C/Gmp program in the

link which is 17 times faster than the Pari routine.

Here there are divisibility rules: If prime(n) and prime(n+1) do

not differ by 6, then n^2+n+1 is a divisor. So finding primes in

this case will be difficult since 5/6 of the numbers are composite at the on set.

If another prime exists, it is larger than 418977 digits.

C. L. Hilliard,Sum of prime indices to respective primes

a(n) = (n+1)^prime(n+1) + n^prime(n) = A062481(n)+A062481(n+1).

For n = 3, 4^7 + 3^5 = 16627, the 3rd entry in the sequence.

(PARI) ppower(n) = { for(x=1, n, y=(x+1)^prime(x+1) + x^prime(x); print1(y", ") ); }

Cf. A160491.

Sequence in context: A012072 A007408 A066989 this_sequence A075987 A135099 A073427

Adjacent sequences: A160498 A160499 A160500 this_sequence A160502 A160503 A160504

nonn

Cino Hilliard (Hillcino368(AT)hotmail.com), May 15 2009

Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 30 2009