A378031 Cogrowth sequence for the 18-element group C6 X C3 = .

1, 1, 2, 85, 926, 5461, 37130, 349525, 2973350, 22369621, 174174002, 1431655765, 11582386286, 91625968981, 729520967450, 5864062014805, 47006639297270, 375299968947541, 2999857885752002, 24019198012642645, 192222214478506046, 1537228672809129301

Offset: 0

Author

Sean A. Irvine, Nov 14 2024

Keywords

• nonn
• easy

Comments

Sequence gives terms for n = 0 (mod 3), all other terms are 0.

Crossrefs

Cf. A095364 (D9), A377627 (C6 X C2), A007613 (C3 X C3), A378109 (S3 X C3), A378110 (S3:C3).

Formula

G.f.: (36*x^4+99*x^3-14*x^2+6*x-1) / ((8*x-1) * (x+1) * (27*x^2+1)).