1,2

Table of n, a(n) for n=1..31.

a(5)=25 converts to 11001 in binary, which has sum of digits equal to 3, and 9=2*5-1 has 3 divisors.

Cf. A114000, A099774 (binary weight), A339916 (bit reversal).

Sequence in context: A006722 A251413 A039774 * A306838 A171879 A171877

Adjacent sequences: A113998 A113999 A114000 * A114002 A114003 A114004

easy,nonn

Paul Barry, Nov 12 2005

Edited by N. J. A. Sloane, Dec 23 2020

approved