A085753 Least k such that n^n + k is a semiprime.

3, 0, 6, 3, 2, 5, 6, 3, 4, 3, 6, 31, 6, 3, 4, 1, 20, 19, 28, 3, 8, 3, 60, 5, 16, 15, 46, 3, 2, 7, 12, 13, 4, 3, 18, 3, 9, 3, 32, 7, 6, 37, 30, 61, 2, 81, 26, 5, 34, 79, 62, 6, 44, 5, 16, 15, 10, 133, 12, 31, 28, 49, 26, 21, 92, 43, 76, 67, 38, 57, 36, 43, 21, 115, 2, 25, 74, 179, 28, 27, 52, 15

Offset

1,1

Links

Sean A. Irvine, Table of n, a(n) for n = 1..100

Dario Alejandro Alpern, Factorization using the Elliptic Curve Method

Mathematica

PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; f[n_] := Block[{k = 0}, While[ PrimeFactorExponentsAdded[n^n + k] != 2, k++ ]; k]; Table[ f[n], {n, 1, 40}]

Prog

(PARI) a(n) = my(k=0); while (bigomega(n^n+k) != 2, k++); k; \\ Michel Marcus, Jul 21 2020

Crossrefs

Cf. A001358 (semiprimes), A089542, A089543, A089544.

Sequence in context: A259659 A005889 A095712 * A120008 A162197 A160770

Adjacent sequences: A085750 A085751 A085752 * A085754 A085755 A085756

Keyword

nonn

Author

Jason Earls, Jul 21 2003

Extensions

Edited and extended by Robert G. Wilson v, Aug 14 2003

Corrected and extended by Ray Chandler, Nov 22 2003

a(69)-a(82) from Max Alekseyev, Jun 13 2009

a(52) and a(73) corrected by Sean A. Irvine, Jul 20 2020

Status

approved