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A037603 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,3,0. 4
1, 13, 130, 1301, 13013, 130130, 1301301, 13013013, 130130130, 1301301301, 13013013013, 130130130130, 1301301301301, 13013013013013, 130130130130130, 1301301301301301 (list; graph; refs; listen; history; text; internal format)
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

a(n) = 10*a(n-1) + (1/9)*(13*(n mod 3) - 2*((n+1) mod 3) + ((n+2) mod 3)), with a(0)=0. - Paolo P. Lava, Jul 30 2009

a(n) = 10*a(n-1) + a(n-3) - 10*a(n-4). G.f.: x*(1+3*x)/((x-1)*(10*x-1)*(1+x+x^2)). - R. J. Mathar, Aug 03 2009

MATHEMATICA

With[{mm=PadRight[{}, 18, {1, 3, 0}]}, Table[FromDigits[Take[mm, n]], {n, 18}]] (* Harvey P. Dale, Dec 13 2011 *)

PROG

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

CROSSREFS

Sequence in context: A255495 A121033 A006100 * A037708 A142740 A248919

Adjacent sequences:  A037600 A037601 A037602 * A037604 A037605 A037606

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified July 29 06:21 EDT 2021. Contains 346340 sequences. (Running on oeis4.)