A328445 a(n) is the smallest prime p such that n = Omega(p^n - 2) = Omega(p^n + 2) where Omega = A001222.

5, 11, 127, 401, 1487, 1153, 6199, 10301, 22193, 72277, 1301423

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Example

5 is a term of a(1) because 1 = Omega(5) = Omega(7),
11 is a term of a(2) because 2 = Omega(119) = Omega(123).

Mathematica

a[n_] := Module[{p = 2}, While[PrimeOmega[p^n - 2] != n || PrimeOmega[p^n + 2] != n, p = NextPrime[p]]; p]; Array[a, 10] (* Amiram Eldar, Oct 15 2019 *)

Prog

(PARI) a(n) = {my(p=3); while (! ((bigomega(p^n-2) == n) && (bigomega(p^n+2) == n)), p = nextprime(p+1)); p; } \\ Michel Marcus, Oct 17 2019

Crossrefs

Cf. A001222 (bigomega), A328359.

Sequence in context: A248253 A262309 A266421 * A094108 A222674 A197538

Adjacent sequences: A328442 A328443 A328444 * A328446 A328447 A328448

Keyword

nonn,more

Author

Juri-Stepan Gerasimov, Oct 15 2019

Extensions

a(11) from Daniel Suteu and Giovanni Resta, Nov 07 2019

Status

approved