Sum of divisors of p+1, p prime.

Terms

a(0) =4a(1) =7a(2) =12a(3) =15a(4) =28a(5) =24a(6) =39a(7) =42a(8) =60a(9) =72a(10) =63a(11) =60a(12) =96a(13) =84a(14) =124a(15) =120a(16) =168a(17) =96a(18) =126a(19) =195a(20) =114a(21) =186a(22) =224a(23) =234a(24) =171a(25) =216a(26) =210a(27) =280a(28) =216a(29) =240