login
A092166
Let M = 2 X 2 matrix [ 1 2 / 5 4 ]; a(n) = (2,1) entry of M^n.
3
5, 25, 155, 925, 5555, 33325, 199955, 1199725, 7198355, 43190125, 259140755, 1554844525, 9329067155, 55974402925, 335846417555, 2015078505325, 12090471031955, 72542826191725, 435256957150355, 2611541742902125
OFFSET
1,1
FORMULA
a(n) = (5*6^n - 5*(-1)^n)/7.
a(n) = A092167(n) +(-1)^n.
From Colin Barker, Nov 08 2012: (Start)
a(n) = 5*a(n-1) + 6*a(n-2).
G.f.: -5*x/((x+1)*(6*x-1)). (End)
MATHEMATICA
Table[ MatrixPower[{{1, 2}, {5, 4}}, n][[2, 1]], {n, 20}] (* Robert G. Wilson v, Apr 22 2004 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Apr 01 2004
EXTENSIONS
Edited by Robert G. Wilson v, Apr 22 2004
STATUS
approved