A147816 Concatenation of n digits 1 and 2(n-1) digits 0.

1, 1100, 1110000, 1111000000, 1111100000000, 1111110000000000, 1111111000000000000, 1111111100000000000000, 1111111110000000000000000, 1111111111000000000000000000, 1111111111100000000000000000000, 1111111111110000000000000000000000

Offset

1,2

Comments

a(n) is also A016152(n) written in base 2.

Links

Paolo Xausa, Table of n, a(n) for n = 1..300

Index entries for linear recurrences with constant coefficients, signature (1100,-100000).

Formula

a(n) = A138119(n)/10.

a(n) = 1100*a(n-1)-100000*a(n-2). G.f.: x / ((100*x-1)*(1000*x-1)). - Colin Barker, Sep 16 2013

Example

n ...... a(n)
1 ....... 1
2 ...... 1100
3 ..... 1110000
4 .... 1111000000
5 ... 1111100000000

Mathematica

Array[(10^#-1)*10^(2*#-2)/9 &, 20] (* or *)
LinearRecurrence[{1100, -100000}, {1, 1100}, 20] (* Paolo Xausa, Feb 27 2024 *)

Prog

(PARI) Vec(x/((100*x-1)*(1000*x-1))  + O(x^100)) \\ Colin Barker, Sep 16 2013

Crossrefs

Cf. A000533, A016152, A135577, A138119, A138120, A138144, A138145, A138146, A138721, A138826, A147757, A147759.

Sequence in context: A078199 A350709 A271472 * A050926 A083933 A080317

Adjacent sequences: A147813 A147814 A147815 * A147817 A147818 A147819

Keyword

base,easy,nonn

Author

Omar E. Pol, Nov 13 2008

Status

approved