|
|
A265052
|
|
Poincaré series for hyperbolic reflection group with Coxeter diagram shown in Comments.
|
|
1
|
|
|
1, 4, 10, 22, 45, 89, 172, 328, 622, 1176, 2220, 4186, 7888, 14859, 27987, 52710, 99268, 186946, 352062, 663010, 1248588, 2351350, 4428075, 8338971, 15703984, 29573802, 55693492, 104882184, 197514502, 371960008, 700476396, 1319139609, 2484208341, 4678269862, 8810134210, 16591275636, 31244748450
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
The Coxeter diagram is:
..5
o---o
|...|
|...|
|...|
o---o
..4
(4 nodes, square, a pair of opposite edges carry labels 4 and 5)
|
|
LINKS
|
Index entries for linear recurrences with constant coefficients, signature (3,-3,2,0,-2,2,0,-2,3,-3,1).
|
|
FORMULA
|
G.f.: -b(4)*(x^3+1)*(x^5+1)/t1 where b(k) = (1-x^k)/(1-x) and t1 = (x-1)*(x^6+x^3+1)*(x^4-2*x^3+x^2-2*x+1).
G.f.: (1+x)^3*(1-x+x^2)*(1+x^2)*(1-x+x^2-x^3+x^4) / ((1-x)*(1-2*x+x^2-2*x^3+x^4)*(1+x^3+x^6)). - Colin Barker, Jan 01 2016
a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3) - 2*a(n-5) + 2*a(n-6) - 2*a(n-8) + 3*a(n-9) - 3*a(n-10) + a(n-11) for n>11. - Vincenzo Librandi, Jan 01 2016
|
|
MATHEMATICA
|
Join[{1}, LinearRecurrence[{3, -3, 2, 0, -2, 2, 0, -2, 3, -3, 1}, {4, 10, 22, 45, 89, 172, 328, 622, 1176, 2220, 4186}, 60]] (* Vincenzo Librandi, Jan 01 2016 *)
|
|
PROG
|
(PARI) Vec((1+x)^3*(1-x+x^2)*(1+x^2)*(1-x+x^2-x^3+x^4) / ((1-x)*(1-2*x+x^2-2*x^3+x^4)*(1+x^3+x^6)) + O(x^50)) \\ Colin Barker, Jan 01 2016
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|