OFFSET
4,2
LINKS
J. Brunvoll, S. J. Cyvin and B. N. Cyvin, Isomer enumeration of polygonal systems..., J. Molec. Struct. (Theochem), 364 (1996), 1-13.
Index entries for linear recurrences with constant coefficients, signature (10,-34,20,148,-328,8,688,-640,-256,640,-256).
FORMULA
G.f.: x^4 * (64*x^13 -32*x^12 -192*x^11 +128*x^10 +212*x^9 -172*x^8 -114*x^7 +110*x^6 +41*x^5 -52*x^4 -3*x^3 +17*x^2 -7*x+1) / ((2*x-1)^5 * (2*x^2-1)^3). - Colin Barker, Nov 30 2012
MAPLE
H := proc(r, alpha, q) local rhalf, alphahalf ; rhalf := floor(r/2) ; alphahalf := floor(alpha/2) ; (binomial(rhalf-1, alphahalf-1)*(q-3) +binomial(rhalf-1, alphahalf))*(q-3)^(rhalf-alphahalf-1) ; end: J := proc(r, alpha, q) (binomial(r-2, alpha-2)*(q-3)^2+2*binomial(r-2, alpha-1) *(q-3)+binomial(r-2, alpha))*(q-3)^(r-alpha-2) ; end: Ifunc := proc(r, alpha, q) J(r, alpha, q)/4+binomial(2, r-alpha)/4+ (1+(-1)^(r+alpha) +(1+(-1)^alpha)*(1-(-1)^r)/2)*H(r, alpha, q)/4 ; end: A121136 := proc(n) Ifunc(n, 4, 5) ; end: for n from 4 to 80 do printf("%d, ", A121136(n)) ; od: # R. J. Mathar, Aug 07 2008
MATHEMATICA
Join[{1, 3, 13}, LinearRecurrence[{10, -34, 20, 148, -328, 8, 688, -640, -256, 640, -256}, {45, 164, 527, 1652, 4876, 14000, 38800, 105112, 278104, 722736, 1846320}, 24]] (* Jean-François Alcover, Mar 31 2020 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Aug 13 2006
EXTENSIONS
Extended beyond a(10) by R. J. Mathar, Aug 07 2008
STATUS
approved