a(n) = a(n-1) + sum of digits of n.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =10a(5) =15a(6) =21a(7) =28a(8) =36a(9) =45a(10) =46a(11) =48a(12) =51a(13) =55a(14) =60a(15) =66a(16) =73a(17) =81a(18) =90a(19) =100a(20) =102a(21) =105a(22) =109a(23) =114a(24) =120a(25) =127a(26) =135a(27) =144a(28) =154a(29) =165