A037545 Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,2,2.

1, 6, 26, 105, 422, 1690, 6761, 27046, 108186, 432745, 1730982, 6923930, 27695721, 110782886, 443131546, 1772526185, 7090104742, 28360418970, 113441675881, 453766703526, 1815066814106, 7260267256425, 29041069025702

Offset

1,2

Links

Table of n, a(n) for n=1..23.

Index entries for linear recurrences with constant coefficients, signature (4,0,1,-4).

Formula

G.f.: x*(1+2*x+2*x^2) / ( (x-1)*(4*x-1)*(1+x+x^2) ). - R. J. Mathar, Apr 30 2015

a(1)=1, a(2)=6, a(3)=26, a(4)=105, a(n)=4*a(n-1)+a(n-3)-4*a(n-4). - Harvey P. Dale, May 22 2015

Mathematica

Module[{nn=30, c}, c=PadRight[{}, nn, {1, 2, 2}]; Table[FromDigits[Take[c, n], 4], {n, nn}]] (* or *) LinearRecurrence[{4, 0, 1, -4}, {1, 6, 26, 105}, 30] (* Harvey P. Dale, May 22 2015 *)

Crossrefs

Sequence in context: A256428 A196860 A254317 * A371438 A027996 A020989

Adjacent sequences: A037542 A037543 A037544 * A037546 A037547 A037548

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved