Sum of divisors of p-1, p prime.

Terms

a(0) =1a(1) =3a(2) =7a(3) =12a(4) =18a(5) =28a(6) =31a(7) =39a(8) =36a(9) =56a(10) =72a(11) =91a(12) =90a(13) =96a(14) =72a(15) =98a(16) =90a(17) =168a(18) =144a(19) =144a(20) =195a(21) =168a(22) =126a(23) =180a(24) =252a(25) =217a(26) =216a(27) =162a(28) =280a(29) =248