1,2

Table of n, a(n) for n=1..48.

The 50th composite is 70 = 2*5*7 and 2+5=7 so a(6)=50.

Cf. A001414.

Sequence in context: A308983 A032826 A190709 * A022133 A212921 A225562

Adjacent sequences: A166729 A166730 A166731 * A166733 A166734 A166735

nonn

Juri-Stepan Gerasimov, Oct 20 2009

Definition clarified, sequence corrected and extended by Charles R Greathouse IV, May 27 2011

approved