a(n) = Sum_{k=1..n} k^2*tau_3(k), where tau_3 is A007425.

Terms

a(0) =1a(1) =13a(2) =40a(3) =136a(4) =211a(5) =535a(6) =682a(7) =1322a(8) =1808a(9) =2708a(10) =3071a(11) =5663a(12) =6170a(13) =7934a(14) =9959a(15) =13799a(16) =14666a(17) =20498a(18) =21581a(19) =28781a(20) =32750a(21) =37106a(22) =38693a(23) =55973a(24) =59723a(25) =65807a(26) =73097a(27) =87209a(28) =89732a(29) =114032