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A138118 Concatenation of 2n-1 digits 1 and n digits 0. 10
10, 11100, 11111000, 11111110000, 11111111100000, 11111111111000000, 11111111111110000000, 11111111111111100000000, 11111111111111111000000000, 11111111111111111110000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..10.

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

a(n)=-(10/9)*10^(n-1)+(100/9)*1000^(n-1), with n>=1 - Paolo P. Lava, Jul 15 2008

EXAMPLE

n .......... a(n)

1 ........... 10

2 ......... 11100

3 ....... 11111000

4 ..... 11111110000

5 ... 11111111100000

MATHEMATICA

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

CROSSREFS

Cf. A138147, A138721.

Cf. A147537. [From Omar E. Pol, Nov 08 2008]

Sequence in context: A267705 A086164 A138119 * A267130 A267850 A267206

Adjacent sequences:  A138115 A138116 A138117 * A138119 A138120 A138121

KEYWORD

easy,nonn,base

AUTHOR

Omar E. Pol, Mar 29 2008

STATUS

approved

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Last modified April 19 10:38 EDT 2019. Contains 322255 sequences. (Running on oeis4.)