A037494 Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 2,1.

2, 19, 173, 1558, 14024, 126217, 1135955, 10223596, 92012366, 828111295, 7453001657, 67077014914, 603693134228, 5433238208053, 48899143872479, 440092294852312, 3960830653670810

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Index entries for linear recurrences with constant coefficients, signature (9,1,-9).

Formula

a(n) = 9*a(n-1) + a(n-2) - 9*a(n-3).

G.f.: x*(2+x)/((1-9*x)*(1-x^2)). a(n) = (19*9^n-4*(-1)^n-15)/80. - Bruno Berselli, Jan 20 2011

Crossrefs

Sequence in context: A037735 A224753 A037558 * A037574 A037742 A037637

Adjacent sequences: A037491 A037492 A037493 * A037495 A037496 A037497

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved