OFFSET
1,4
COMMENTS
Subsequence of A025474.
EXAMPLE
a(9) = 4 is the exponent of 81 = A264734(9) = 3^4.
MATHEMATICA
t = Prepend[Select[Range@ 100000, AllTrue[{# - 2, #, # + 2}, PrimePowerQ] &], 3]; Flatten@ Map[Last, FactorInteger@ # &@ t, {2}] (* Michael De Vlieger, Dec 03 2015, Version 10 *)
PROG
(PARI) is(k) = isprimepower(k) || k==1;
for(k=1, 1e6, if(is(k) && is(k+2) && is(k-2), print1(bigomega(k), ", "))) \\ Altug Alkan, Nov 23 2015
CROSSREFS
KEYWORD
nonn,more,less
AUTHOR
Juri-Stepan Gerasimov, Nov 22 2015
STATUS
approved