A037511 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,2,0.

1, 12, 120, 1201, 12012, 120120, 1201201, 12012012, 120120120, 1201201201, 12012012012, 120120120120, 1201201201201, 12012012012012, 120120120120120, 1201201201201201

Offset

1,2

Links

Table of n, a(n) for n=1..16.

Index entries for linear recurrences with constant coefficients, signature (10,0,1,-10).

Formula

G.f.: x*(1+2*x) / ( (x-1)*(10*x-1)*(1+x+x^2) ). - R. J. Mathar, Aug 04 2013

Mathematica

Table[FromDigits[PadRight[{}, n, {1, 2, 0}]], {n, 20}] (* or *) LinearRecurrence[{10, 0, 1, -10}, {1, 12, 120, 1201}, 20] (* Harvey P. Dale, Jan 03 2023 *)

Prog

(PARI) Vec(x*(1+2*x)/((x-1)*(10*x-1)*(1+x+x^2)) + O(x^30)) \\ Jinyuan Wang, Apr 14 2020

Crossrefs

Sequence in context: A129332 A004291 A001754 * A037694 A242810 A067102

Adjacent sequences: A037508 A037509 A037510 * A037512 A037513 A037514

Keyword

nonn,base

Author

Clark Kimberling

Status

approved