A300478 Numbers n where more than one positive integer k with 1 < k < n exists such that n^k + k^n is prime.

114, 318, 590, 790, 903, 1036, 1158, 1263, 1298, 1545, 1588, 2007

Offset

1,1

Comments

Numbers n such that A300477(n) > 1.

Subsequence of A162488.

Links

Table of n, a(n) for n=1..12.

Example

114 is a term of the sequence, since 114^k + k^114 is prime for two values of k with 1 < k < 114, namely, k=67 and k=97.

Prog

(PARI) a300477(n) = my(i=0); for(k=2, n-1, if(ispseudoprime(n^k+k^n), i++)); i
is(n) = a300477(n) > 1

Crossrefs

Cf. A162488, A300477.

Sequence in context: A171374 A228962 A250725 * A305066 A322541 A323758

Adjacent sequences: A300475 A300476 A300477 * A300479 A300480 A300481

Keyword

nonn,hard,more

Author

Felix Fröhlich, Mar 06 2018

Extensions

a(7)-a(11) from Robert Israel, Sep 25 2020

a(12) from Michael S. Branicky, Apr 26 2023

Status

approved