Place where n-th 1 occurs in A023129.

Terms

a(0) =1a(1) =3a(2) =7a(3) =12a(4) =19a(5) =28a(6) =38a(7) =50a(8) =64a(9) =79a(10) =96a(11) =115a(12) =135a(13) =157a(14) =181a(15) =206a(16) =233a(17) =262a(18) =292a(19) =324a(20) =357a(21) =392a(22) =429a(23) =467a(24) =507a(25) =549a(26) =592a(27) =637a(28) =684a(29) =732