OFFSET
1,1
COMMENTS
All a(n) are powers of 2.
No terms are powers of 8. - Robert Israel, Jan 07 2019
LINKS
Robert Israel, Table of n, a(n) for n = 1..150
EXAMPLE
2 is in this sequence because both 2 - 1 = 1 and 2 + 1 = 3 are squarefree.
MAPLE
map(t -> 2^t, select(t -> numtheory:-issqrfree(2^t-1) and numtheory:-issqrfree(2^t+1), [seq(seq(3*k+i, i=1..2), k=0..20)])); # Robert Israel, Jan 07 2019
PROG
(Magma) [2^n: n in [1..50] | IsSquarefree(2^n-1) and IsSquarefree(2^n+1)];
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Apr 30 2016
STATUS
approved