OFFSET
1,1
COMMENTS
Somewhat astonishingly, n = 89 is the only number below 173 for which the least prime factor is different from the least k > 1 which divides n + 2^k - 2. For larger n, this property becomes more frequent.
The first composite number in this sequence is a(105) = 3239.
PROG
(PARI) my(aa(n)=for(k=2, 9e9, Mod(2, k)^k+n-2||return(k))); for(n=2, 1e5, aa(n)!=factor(n)[1, 1]&&print1(n", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Aug 11 2015
STATUS
approved