A103422 Number of compositions of n in which the greatest part is even.

0, 1, 2, 5, 9, 18, 34, 66, 127, 249, 490, 972, 1936, 3874, 7772, 15623, 31439, 63308, 127506, 256782, 516970, 1040340, 2092450, 4206146, 8449953, 16965459, 34042784, 68272206, 136847328, 274168858, 549042730, 1099050180, 2199222960

Offset

1,3

Links

Table of n, a(n) for n=1..33.

Formula

G.f.: Sum((1-x)^2*x^(2*n)/((1-2*x+x^(2*n))*(1-2*x+x^(2*n+1))), n=1..infinity).

Mathematica

Rest[ CoefficientList[ Series[ Expand[ Sum[(1 - x)^2*x^(2n)/((1 - 2x + x^(2n))*(1 - 2x + x^(2n + 1))), {n, 35}]], {x, 0, 35}], x]] (* Robert G. Wilson v, Feb 05 2005 *)

Crossrefs

Cf. A103419, A103420, A103421, A027187, A027193, A026804, A026805.

Sequence in context: A342208 A077865 A117353 * A217210 A351983 A247322

Adjacent sequences: A103419 A103420 A103421 * A103423 A103424 A103425

Keyword

easy,nonn

Author

Vladeta Jovovic, Feb 04 2005

Extensions

More terms from Robert G. Wilson v, Feb 05 2005

Status

approved