OFFSET
1,2
COMMENTS
Nonsquare semiprimes pq for which F(pq) is also a semiprime is given by the positions where 25's occur in this sequence: 10, 14, 22, 26, 34, 94, (any more terms?). This is a subsequence of A072381.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..1300 (based also on the b-file of A278245 provided by Hans Havermann)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 17 2017
STATUS
approved