A200047 Number of compositions of n having smallest part equal to 2.

0, 1, 0, 1, 2, 3, 5, 9, 15, 25, 42, 70, 116, 192, 317, 522, 858, 1408, 2307, 3775, 6170, 10074, 16433, 26784, 43623, 71002, 115497, 187777, 305147, 495669, 804839, 1306404, 2119884, 3438952, 5577396, 9043549, 14660810, 23762784, 38509220, 62397495, 101090631

Offset: 1

Author

Alois P. Heinz, Nov 13 2011

Keywords

• nonn

Examples

			a(7) = 5: [2,2,3], [2,3,2], [2,5], [3,2,2], [5,2].
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..1000

Crossrefs

Column k=2 of A105147.

Programs

Maple

a:= n-> (<<0|1|0|0|0>, <0|0|1|0|0>, <0|0|0|1|0>, <0|0|0|0|1>, <-1|-1|0|0|2>>^n. <<0, 0, 1, 0, 1>>)[1, 1]: seq (a(n), n=1..50);

Formula

G.f.: (x-1)^2*x^2/(1-2*x+x^4+x^5).