A033128 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,0,1.

1, 10, 101, 1011, 10110, 101101, 1011011, 10110110, 101101101, 1011011011, 10110110110, 101101101101, 1011011011011, 10110110110110, 101101101101101, 1011011011011011, 10110110110110110, 101101101101101101, 1011011011011011011, 10110110110110110110

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = 10*a(n-1) +a(n-3) -10*a(n-4). G.f.: x*(1+x^2)/((x-1) * (10*x-1) * (1+x+x^2)). - R. J. Mathar, Oct 05 2009

a(n) = floor((101/999)*10^n). - Tani Akinari, Jul 22 2015

Mathematica

nn=20; With[{c=PadRight[{}, nn, {1, 0, 1}]}, Table[FromDigits[ Take[ c, n]], {n, nn}]] (* Harvey P. Dale, Dec 30 2012 *)

Crossrefs

Sequence in context: A284179 A096883 A266720 * A094945 A190480 A267623

Adjacent sequences: A033125 A033126 A033127 * A033129 A033130 A033131

Keyword

nonn,base

Author

Clark Kimberling

Extensions

More terms from Harvey P. Dale, Dec 30 2012

Status

approved