A303121 Least k>1 such that k^n + n is prime, 0 if no such k exists.

2, 3, 2, 0, 2, 175, 16, 3, 2, 539, 32, 221, 118, 417, 2, 85, 14, 133, 22, 81, 76, 115, 12, 55, 28, 15, 0, 2465, 110, 31, 232, 117, 230, 3, 12, 851, 4, 375, 2, 1599, 48, 5461, 46, 15, 218, 6815, 78, 7, 100, 993, 28, 901, 624, 13, 252, 183, 226, 43247, 104, 5063, 1348, 777, 1294, 0, 1806

Offset: 1

Author

Hugo Pfoertner, Apr 23 2018

Keywords

• nonn

Comments

The values of n for which k^n + n is reducible over the integers are given in A097792. - Joseph Myers, Allan C. Wechsler Apr 16 2018

Examples

			a(2) = 3 because 3^2 + 3 = A303122(2) = 11 is prime, whereas 2^2 + 2 = 6 is composite.
		

Links

• Hugo Pfoertner, Table of n, a(n) for n = 1..365

Crossrefs

Cf. A072883, A093324, A097764, A097792, A303122.

Formula

If n + 1 is composite, then a(n) = A072883(n). - Altug Alkan, Apr 23 2018