801626558481domain: NAppears in sequencesa(n) = (-1)^(n+1)/3/(2n+1) * Sum_{k=0..n} 16^k*B(2k)*C(2n+1,2k) where B(k) denotes the k-th Bernoulli number.at n=8A076552A141479(n+1)/3.at n=17A147719