OFFSET
1,4
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (0, 20, 0, -99).
FORMULA
a(n)=20*a(n-2)-99*a(n-4). G.f.: -x^2*(-1-x+10*x^2)/((3*x-1)*(3*x+1)*(11*x^2-1)). [From R. J. Mathar, Jul 13 2009]
EXAMPLE
As pairs:
0, 1
1, 10
20, 101
301, 1030
4040, 10601
51001, 110050
620060, 1151501
7352101, 12135070
85656080, 128702801
MATHEMATICA
nxt[{n_, a_, b_, c_}]:={n+1, b, c, If[OddQ[n], c+10b, a+10b]}; NestList[nxt, {2, 0, 1, 1}, 30][[All, 2]] (* or *) LinearRecurrence[{0, 20, 0, -99}, {0, 1, 1, 10}, 30] (* Harvey P. Dale, May 03 2018 *)
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Mark Dols, Jun 24 2009, Jun 28 2009, Jul 13 2009
EXTENSIONS
Edited by N. J. A. Sloane, Jun 30 2009
NAME adapted to offset. - R. J. Mathar, Jun 19 2021
STATUS
approved