|
|
A157880
|
|
Expansion of 136*x^2 / (-x^3+1155*x^2-1155*x+1).
|
|
2
|
|
|
0, 136, 157080, 181270320, 209185792336, 241400223085560, 278575648254944040, 321476056685982336736, 370983090839975361649440, 428114165353274881361117160, 494043375834588373115367553336, 570125627598949629300252795432720, 657924480205812037624118610561805680
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
This sequence is part of a solution of a more general problem involving two equations, three sequences a(n), b(n), c(n) and a constant A:
A * c(n)+1 = a(n)^2,
(A+1) * c(n)+1 = b(n)^2, for details see comment in A157014.
A157880 is the c(n) sequence for A=8.
|
|
LINKS
|
|
|
FORMULA
|
G.f.: 136*x^2/(-x^3+1155*x^2-1155*x+1).
c(1) = 0, c(2) = 136, c(3) = 1155*c(2), c(n) = 1155 * (c(n-1)-c(n-2)) + c(n-3) for n>3.
a(n) = -((577+408*sqrt(2))^(-n)*(-1+(577+408*sqrt(2))^n)*(17+12*sqrt(2)+(-17+12*sqrt(2))*(577+408*sqrt(2))^n))/288. - Colin Barker, Jul 25 2016
|
|
MATHEMATICA
|
LinearRecurrence[{1155, -1155, 1}, {0, 136, 157080}, 20] (* Harvey P. Dale, Dec 04 2019 *)
|
|
PROG
|
(PARI) a(n) = round(-((577+408*sqrt(2))^(-n)*(-1+(577+408*sqrt(2))^n)*(17+12*sqrt(2)+(-17+12*sqrt(2))*(577+408*sqrt(2))^n))/288) \\ Colin Barker, Jul 25 2016
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|