A037624 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 2,0,3.

2, 20, 203, 2032, 20320, 203203, 2032032, 20320320, 203203203, 2032032032, 20320320320, 203203203203, 2032032032032, 20320320320320, 203203203203203, 2032032032032032, 20320320320320320, 203203203203203203, 2032032032032032032, 20320320320320320320

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..200
• Index entries for linear recurrences with constant coefficients, signature (10,0,1,-10).

Programs

Magma

I:=[2,20,203,2032]; [n le 4 select I[n] else 10*Self(n-1)+Self(n-3)-10*Self(n-4): n in [1..30]]; // Vincenzo Librandi, Feb 16 2018

Mathematica

CoefficientList[Series[(2 + 3 x^2) / ((x - 1) (10 x - 1) (1 + x + x^2)), {x, 0, 20}], x] (* Vincenzo Librandi, Feb 16 2018 *)
Table[FromDigits[PadRight[{},n,{2,0,3}]],{n,20}] (* Harvey P. Dale, Jul 29 2024 *)

Formula

G.f.: x*(2+3*x^2) / ( (x-1)*(10*x-1)*(1+x+x^2) ). - R. J. Mathar, Nov 21 2011