OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
A097378(a(n)) is prime.
MATHEMATICA
f[p_, e_] := p^(1 + Min[e, 2]); s[1] = 2; s[n_] := 1 + Times @@ f @@@ FactorInteger[n]; Select[Range[650], PrimeQ[s[#]] &] (* Amiram Eldar, Feb 01 2024 *)
PROG
(PARI) is(n) = {my(f = factor(n)); isprime(1 + prod(i = 1, #f~, f[i, 1]^(1 + min(f[i, 2], 2)))); } \\ Amiram Eldar, Feb 01 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Aug 11 2004
STATUS
approved