Sum of the divisors of 7^n-1.

Terms

a(0) =12a(1) =124a(2) =780a(3) =7812a(4) =33624a(5) =354640a(6) =1704240a(7) =18929096a(8) =97036800a(9) =800520192a(10) =3958188480a(11) =56928231360a(12) =193778020824