A037617 - OEIS

A037617

Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,3,2.

1, 13, 132, 1321, 13213, 132132, 1321321, 13213213, 132132132, 1321321321, 13213213213, 132132132132, 1321321321321, 13213213213213, 132132132132132, 1321321321321321, 13213213213213213, 132132132132132132, 1321321321321321321, 13213213213213213213, 132132132132132132132

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..21.

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

FORMULA

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

a(n) ~ (44/333)*10^n = (44/333)*A011557(n). - Stefano Spezia, Oct 15 2023

MATHEMATICA

Table[FromDigits[PadRight[{}, n, {1, 3, 2}]], {n, 20}] (* Harvey P. Dale, Mar 29 2015 *)

CROSSREFS