1,1

Table of n, a(n) for n=1..56.

14 is in the sequence as 14=2*7 and 2+7=9, an odd composite; 60 is not, as 60=2^2*3*5 and 2+5 is 7, not composite.

Cf. A002808.

Sequence in context: A256573 A030786 A094163 * A105583 A323030 A005277

Adjacent sequences: A134834 A134835 A134836 * A134838 A134839 A134840

nonn

Juri-Stepan Gerasimov, Jan 04 2009

Definition and examples simplified by D. S. McNeil, Dec 10 2009

Corrected and extended by D. S. McNeil, Dec 10 2009

approved