a(n) = Sum_{k=1..n} sigma_2(k)^2.

Terms

a(0) =1a(1) =26a(2) =126a(3) =567a(4) =1243a(5) =3743a(6) =6243a(7) =13468a(8) =21749a(9) =38649a(10) =53533a(11) =97633a(12) =126533a(13) =189033a(14) =256633a(15) =372914a(16) =457014a(17) =664039a(18) =795083a(19) =1093199a(20) =1343199a(21) =1715299a(22) =1996199a(23) =2718699a(24) =3142500a(25) =3865000a(26) =4537400a(27) =5639900a(28) =6348864a(29) =8038864