A138118 Concatenation of 2n-1 digits 1 and n digits 0.

10, 11100, 11111000, 11111110000, 11111111100000, 11111111111000000, 11111111111110000000, 11111111111111100000000, 11111111111111111000000000, 11111111111111111110000000000

Offset: 1

Author

Omar E. Pol, Mar 29 2008

Keywords

• easy
• nonn
• base

Comments

a(n) is also A147537(n) written in base 2. [From Omar E. Pol, Nov 08 2008]

Examples

			n .......... a(n)
1 ........... 10
2 ......... 11100
3 ....... 11111000
4 ..... 11111110000
5 ... 11111111100000
		

Links

• Index entries for linear recurrences with constant coefficients, signature (1010,-10000)

Crossrefs

Cf. A138147, A138721.

Cf. A147537.

Programs

Mathematica

FromDigits/@Table[Join[PadRight[{},2n-1,1],PadRight[{},n,0]],{n,15}] (* Harvey P. Dale, Dec 09 2011 *)

Formula

O.g.f.: 10*(1+100x)/[(-1+1000x)*(-1+10x)]. a(n)=A100706(n)*10^n = 10*a(n-1)+11*1000^n. - R. J. Mathar, Apr 03 2008