Place where n-th 1 occurs in A023133.

Terms

a(0) =1a(1) =5a(2) =12a(3) =22a(4) =35a(5) =51a(6) =70a(7) =92a(8) =118a(9) =147a(10) =179a(11) =214a(12) =252a(13) =293a(14) =337a(15) =385a(16) =436a(17) =490a(18) =547a(19) =607a(20) =670a(21) =736a(22) =806a(23) =879a(24) =955a(25) =1034a(26) =1116a(27) =1201a(28) =1289a(29) =1381