A131959 Numbers k such that 1 + Product_{j=1..k} prime(j)^prime(k-j+1) is prime.

1, 2, 3, 8

Offset

1,2

Comments

A131958 gives the corresponding primes.

Links

Table of n, a(n) for n=1..4.

Example

1 + (2^5)*(3^3)*(5^2) = 21601 is the prime for the term 3.

Prog

(PARI) isok(k) = isprime(1 + prod(j=1, k, prime(j)^prime(k-j+1))); \\ Michel Marcus, Jan 09 2021

Crossrefs

Cf. A131958.

Sequence in context: A201363 A088332 A357064 * A202688 A021046 A138180

Adjacent sequences: A131956 A131957 A131958 * A131960 A131961 A131962

Keyword

hard,nonn,more

Author

Rick L. Shepherd, Aug 01 2007

Status

approved