A109119 a(n) = 2(5n^2 + 5n + 1)^3.

2, 2662, 59582, 453962, 2060602, 6885902, 18787862, 44376082, 94091762, 183467702, 334568302, 577609562, 952759082, 1512116062, 2321871302, 3464647202, 5042017762, 7177208582, 10017976862, 13739671402, 18548472602

Offset: 0

Author

Emeric Deutsch, Jun 19 2005

Keywords

• nonn
• easy

Comments

Kekulé numbers for certain benzenoids.

References

• S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 310).

Programs

Maple

a:=n->2*(5*n^2+5*n+1)^3: seq(a(n),n=0..28);

Formula

G.f.: 2(1 + 1324z + 20495z^2 + 46360z^3 + 20495z^4 + 1324z^5 + z^6)/(1-z)^7.

a(n) = 2*A062786(n)^3. - R. J. Mathar, Jul 22 2022