A377627 Cogrowth sequence of the 12-element group C6 X C2 = .

1, 1, 1, 2, 29, 211, 926, 3095, 9829, 37130, 164921, 728575, 2973350, 11450531, 43942081, 174174002, 708653429, 2884834891, 11582386286, 46006694735, 182670807229, 729520967450, 2926800830801, 11743814559415, 47006639297270, 187791199242011, 750176293590361

Offset: 0

Author

Sean A. Irvine, Nov 02 2024

Keywords

• nonn
• easy

Comments

Gives the even terms, all the odd terms are 0.

Examples

			a(2)=1 corresponds to the word TTTT.
a(3)=2 corresponds to the words SSSSSS and TTTTTT.
		

Crossrefs

Cf. A007583 (D6), A377626 (A4), A377656 (Dic12), A377714 (C4 X C2), A377840 (C8 X C2).

Formula

G.f.: (6*x^5+5*x^4+11*x^3-10*x^2+5*x-1) / ((4*x-1) * (x^2+x+1) * (9*x^2-3*x+1)).