A158772 a(n) = A138635(n+18)-A138635(n).

21, 21, 21, 42, 42, 42, 84, 84, 84, 168, 168, 168, 336, 336, 336, 672, 672, 672, 1344, 1344, 1344, 2688, 2688, 2688, 5376, 5376, 5376, 10752, 10752, 10752, 21504, 21504, 21504, 43008, 43008, 43008, 86016, 86016, 86016, 172032, 172032, 172032, 344064

Offset

0,1

Comments

a(n) divided by 21 is the sequence 1,1,1,2,2,2,4,4,4,.., that is A000079 triplicated.

Links

Table of n, a(n) for n=0..42.

Crossrefs

Sequence in context: A154352 A291433 A010860 * A151910 A040421 A022355

Adjacent sequences: A158769 A158770 A158771 * A158773 A158774 A158775

Keyword

nonn,less

Author

Paul Curtz, Mar 26 2009

Extensions

Edited by R. J. Mathar, May 17 2009

Status

approved