a(n) = 1 + sigma(n)^3 + sigma(n)^6.

Terms

a(0) =3a(1) =757a(2) =4161a(3) =117993a(4) =46873a(5) =2987713a(6) =262657a(7) =11394001a(8) =4829007a(9) =34018057a(10) =2987713a(11) =481912257a(12) =7532281a(13) =191116801a(14) =191116801a(15) =887533473a(16) =34018057a(17) =3518803081a(18) =64008001a(19) =5489105833a(20) =1073774593a(21) =2176828993a(22) =191116801a(23) =46656216001a(24) =887533473a(25) =5489105833