1,2

This is not the digital root (A010888) but the digital sum (A007953).

a(2^k)=10^k.

Table of n, a(n) for n=1..39.

Cf. A077195, A077196.

Sequence in context: A260680 A111126 A165790 * A038305 A089478 A028967

Adjacent sequences: A077191 A077192 A077193 * A077195 A077196 A077197

base,nonn

Amarnath Murthy, Nov 01 2002

Edited by Robert G. Wilson v, Nov 05 2002

Corrected by Matthew Vandermast, Apr 12 2003

a(34) corrected by Max Alekseyev, Feb 26 2009

a(38) corrected by Paul Tek, Mar 14 2013

approved