OFFSET
1,1
COMMENTS
The only known primes in the sequence are 3, 23.
FORMULA
a(n) = (A086816(n) + 1)/6. - Alois P. Heinz, Sep 18 2024
PROG
(PARI) lista(nn) = {for (n = 1, nn, trg = n*(n+1)/2; if (!(trg % 2) && isprime(trg/2-1) && isprime(trg/2+1), print1(trg/12, ", ")); ); } \\ Michel Marcus, Oct 16 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Oct 07 2009
STATUS
approved