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A037694 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,2,0,3. 0
1, 12, 120, 1203, 12031, 120312, 1203120, 12031203, 120312031, 1203120312, 12031203120, 120312031203, 1203120312031, 12031203120312, 120312031203120, 1203120312031203, 12031203120312031, 120312031203120312, 1203120312031203120, 12031203120312031203 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..20.

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

FORMULA

a(n) = 10*a(n-1) + (1/4)*(-2*(n mod 4) + 3*((n+1) mod 4) + 3*((n+3) mod 4)), with a(0)=0. - Paolo P. Lava, Jul 30 2009

G.f.: x*(1+2*x+3*x^3) / ( (x-1)*(10*x-1)*(1+x)*(x^2+1) ). - R. J. Mathar, Aug 12 2013

MATHEMATICA

Table[FromDigits[PadRight[{}, n, {1, 2, 0, 3}]], {n, 30}] (* Harvey P. Dale, Oct 18 2016 *)

PROG

(PARI) Vec(x*(1+2*x+3*x^3)/((x-1)*(10*x-1)*(1+x)*(x^2+1)) + O(x^25)) \\ Jinyuan Wang, Apr 14 2020

CROSSREFS

Sequence in context: A004291 A001754 A037511 * A242810 A067102 A129064

Adjacent sequences:  A037691 A037692 A037693 * A037695 A037696 A037697

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling

EXTENSIONS

More terms from Harvey P. Dale, Oct 18 2016

STATUS

approved

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Last modified August 2 03:55 EDT 2021. Contains 346409 sequences. (Running on oeis4.)