2532161domain: NPropertiesPrimalityPrimeyesAppears in sequences(3^p+p)/(p+1) with (p + 1) odd prime > 3.at n=4A121823a(n) = (1/(2*n)) * Sum_{d|n} 3^(n/d-1) * phi(3*d).at n=16A364210Prime numbersat n=185276