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A037511
Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,2,0.
5
1, 12, 120, 1201, 12012, 120120, 1201201, 12012012, 120120120, 1201201201, 12012012012, 120120120120, 1201201201201, 12012012012012, 120120120120120, 1201201201201201
OFFSET
1,2
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
KEYWORD
nonn,base
STATUS
approved