OFFSET
2,1
COMMENTS
For n == 1 (mod 4) (n not 1), a(n) <= (n + 1)/2.
For n == 3 (mod 4), a(n) = 1.
For even n, a(n) <= n + 1.
Existence proof for n >= 2 and upper bounds use the binomial formula.
PROG
(PARI) for(n=2, 79, for(k=1, n+1, !issquarefree(n^k+1)&!print1(k", ")&break))
CROSSREFS
KEYWORD
nonn
AUTHOR
Gionata Neri, Apr 18 2020
STATUS
approved