A177832 Smallest k > 0 such that k^prime(n) + prime(n) is prime.

1, 2, 2, 16, 32, 118, 14, 22, 12, 110, 232, 4, 48, 46, 78, 624, 104, 1348, 306, 30, 834, 400, 402, 2, 66, 8, 316, 618, 390, 560, 996, 1086, 774, 178, 300, 1912, 1792, 120, 614, 2024, 1854, 1258, 698, 966, 602, 2668, 3712, 294, 560, 108, 524, 3962, 2838, 870, 546

Offset

1,2

Links

Table of n, a(n) for n=1..55.

Example

1^prime(1)+prime(1) = 1^2+2 = 3 is prime, hence a(1) = 1.
1^prime(2)+prime(2) = 1^3+3 = 4 is not prime, but 2^prime(2)+prime(2) = 2^3+3 = 11 is prime, hence a(2) = 2.
k^prime(4)+prime(4) is not prime for k < 16, but 16^prime(4)+prime(4) = 16^7+7 = 268435463 is prime, hence a(4) = 16.
a(18)^prime(18)+prime(18) = 1348^61+61 has 191 digits.

Prog

(PARI) a177832(n) = {local(k=1, p=prime(n)); while(!isprime(k^p+p), k+=1); k}

Crossrefs

Cf. A000040, A084047.

Sequence in context: A113123 A353912 A303567 * A230800 A363236 A076615

Adjacent sequences: A177829 A177830 A177831 * A177833 A177834 A177835

Keyword

nonn

Author

Ulrich Krug (leuchtfeuer37(AT)gmx.de), May 14 2010

Extensions

Edited, non-specific references and keywords base, hard removed, PARI program and terms a(21) through a(55) added by the Associate Editors of the OEIS

Status

approved