A205088 a(n)=n 8's sandwiched between two 1's.

11, 181, 1881, 18881, 188881, 1888881, 18888881, 188888881, 1888888881, 18888888881, 188888888881, 1888888888881, 18888888888881, 188888888888881, 1888888888888881, 18888888888888881, 188888888888888881, 1888888888888888881, 18888888888888888881

Offset

0,1

Links

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (11,-10).

Formula

a(0) = 11, a(n) = 10*a(n-1) + 71.

a(n) = 1/9*(17*10^(n+1)-71). [From Alexander R. Povolotsky, Jan 25 2012]

Mathematica

a[0]=11; a[n_] := a[n-1]*10+71; Table[a[n], {n, 0, 44}]
Table[FromDigits[Join[{1}, PadRight[{}, n, 8], {1}]], {n, 0, 20}] (* Harvey P. Dale, Apr 15 2012 *)

Prog

(PARI) a(n)=(170*10^n-71)/9 \\ Charles R Greathouse IV, Jan 23 2012

Crossrefs

Sequence in context: A106907 A020456 A036935 * A241193 A143413 A009118

Adjacent sequences: A205085 A205086 A205087 * A205089 A205090 A205091

Keyword

nonn,easy,less,base

Author

José María Grau Ribas, Jan 22 2012

Status

approved