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A092167
Let M = 2 X 2 matrix [ 1 2 / 5 4 ]; a(n) = (2,2) entry of M^n.
3
4, 26, 154, 926, 5554, 33326, 199954, 1199726, 7198354, 43190126, 259140754, 1554844526, 9329067154, 55974402926, 335846417554, 2015078505326, 12090471031954, 72542826191726, 435256957150354, 2611541742902126
OFFSET
1,1
FORMULA
a(n) = (5*6^n + 2*(-1)^n)/7.
A092166 -(-1)^n.
From R. J. Mathar, Apr 20 2009: (Start)
a(n) = 5*a(n-1) + 6*a(n-2).
G.f.: 2*x*(2+3*x)/((1+x)*(1-6*x)). (End)
MATHEMATICA
Table[ MatrixPower[{{1, 2}, {5, 4}}, n][[2, 2]], {n, 20}] (* Robert G. Wilson v, Apr 22 2004 *)
CROSSREFS
KEYWORD
nonn
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