1,9

When a(n)=1, then A173931(n) is in sequence A173793.

T. D. Noe, Table of n, a(n) for n=1..185

First /@ Last[Transpose[cantor]] (* see A173931 *)

Cf. A173931, A173793, A173934.

Sequence in context: A008945 A008705 A327242 * A249649 A226571 A274030

Adjacent sequences: A173929 A173930 A173931 * A173933 A173934 A173935

nonn

T. D. Noe, Mar 03 2010

Name qualified by Peter Munn, Jul 12 2019

approved