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

Author

Omar E. Pol, Nov 13 2008

Keywords

• base
• easy
• nonn

Comments

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

Examples

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

Links

• Paolo Xausa, Table of n, a(n) for n = 1..300
• Index entries for linear recurrences with constant coefficients, signature (1100,-100000).

Crossrefs

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

Programs

Mathematica

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

PARI

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

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