1,1

All terms are primes.

a(4) is certified prime by primo; a(5) is prp. - Ray G. Opao (1260(AT)email.com), Aug 02 2007

k=13; Do[ p=Prime[n]; f=(3^p+k^p)/(k+3); If[ PrimeQ[f], Print[p]], {n, 1, 100} ]

Cf. A007658 = numbers n such that (3^n + 1)/4 is prime. Cf. A057469 = numbers n such that (3^n + 2^n)/5 is prime. Cf. A122853 = numbers n such that (3^n + 5^n)/8 is prime. Cf. A128066, A128067, A128068, A128069, A128070, A128072, A128073, A128074, A128075. Cf. A059801 = numbers n such that 4^n - 3^n is prime. Cf. A121977 = numbers n such that (5^n - 3^n)/2 is a prime. Cf. A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032.

Sequence in context: A139159 A042329 A125956 this_sequence A079622 A005844 A012636

Adjacent sequences: A128068 A128069 A128070 this_sequence A128072 A128073 A128074

hard,more,nonn

Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 14 2007

One more term from Ray G. Opao (1260(AT)email.com), Aug 02 2007