OFFSET
1,4
COMMENTS
Even terms occur on square n, odd terms on nonsquare n.
Numbers k such that a(k) = 2^e for e >= 1, are: 4, 25, 841, 12769, 66896041, etc., i.e., terms of A073715 squared.
LINKS
FORMULA
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Aug 05 2020
EXTENSIONS
Comments edited by Antti Karttunen, Jul 03 2023
STATUS
approved