A037761 Base-7 digits are, in order, the first n terms of the periodic sequence with initial period 3,0,1,2.

3, 21, 148, 1038, 7269, 50883, 356182, 2493276, 17452935, 122170545, 855193816, 5986356714, 41904497001, 293331479007, 2053320353050, 14373242471352, 100612697299467, 704288881096269, 4930022167673884

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (7,0,0,1,-7).

Formula

From Colin Barker, Apr 30 2014: (Start)

a(n) = (-100-25*(-1)^n-(24-i*32)*(-i)^n-(24+32*i)*i^n+173*7^n)/400, where i=sqrt(-1).

a(n) = 7*a(n-1)+a(n-4)-7*a(n-5).

G.f.: x*(2*x^3+x^2+3) / ((x-1)*(x+1)*(7*x-1)*(x^2+1)). (End)

Mathematica

CoefficientList[Series[(2 x^3 + x^2 + 3)/((x - 1) (x + 1) (7 x - 1) (x^2 + 1)), {x, 0, 30}], x] (* Vincenzo Librandi, May 01 2014 *)

Prog

(PARI) Vec(x*(2*x^3+x^2+3)/((x-1)*(x+1)*(7*x-1)*(x^2+1)) + O(x^100)) \\ Colin Barker, Apr 30 2014

Crossrefs

Sequence in context: A088088 A206638 A357652 * A037649 A037768 A037656

Adjacent sequences: A037758 A037759 A037760 * A037762 A037763 A037764

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved