

A085753


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


4



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
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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



