OFFSET
1,4
LINKS
PROG
(PARI) is(p) = {my(s=0); if(isprime(p), for(i=1, (p-1)/2, if((s+=kronecker(i, p))<0, return(1)))); 0; }
a(n) = sum(p=2^n+1, 2^(n+1), is(p)); \\ Jinyuan Wang, Jul 20 2020
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Antti Karttunen, Jun 01 2004
STATUS
approved