A191355 Indices of terms in A069748 with two decimal digits 1 and all others 0.
5, 6, 8, 9, 12, 15, 18, 22, 27, 31, 37, 43, 49, 56, 64, 71, 80, 89, 98, 108
Offset: 1
Formula
Conjectural formula: a(n) = 5 + Sum_{i=1..n-1} A105637(i).
Equivalent conjecture: a(n) = -(-1)^n/8 + A049347(n)/3 + 115/24 + n/6 + n^2/4. - R. J. Mathar, Jul 11 2011
Extensions
a(18)-a(20), using A002780 b-file, added by Michel Marcus, Apr 17 2023