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

Terms

a(0) =1a(1) =11a(2) =41a(3) =125a(4) =255a(5) =555a(6) =905a(7) =1585a(8) =2404a(9) =3704a(10) =5046a(11) =7566a(12) =9776a(13) =13276a(14) =17176a(15) =22632a(16) =27562a(17) =35752a(18) =42630a(19) =53550a(20) =64050a(21) =77470a(22) =89660a(23) =110060a(24) =126335a(25) =148435a(26) =170575a(27) =199975a(28) =224393a(29) =263393