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A138119 Concatenation of n digits 1 and 2n-1 digits 0. 7
10, 11000, 11100000, 11110000000, 11111000000000, 11111100000000000, 11111110000000000000, 11111111000000000000000, 11111111100000000000000000, 11111111110000000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) has 3n-1 digits.

a(n) is also A147538(n) written in base 2. [From Omar E. Pol, Nov 08 2008]

LINKS

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

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

FORMULA

a(n) = [(10^n-1)*10^(2n-1)]/9. [ Paolo P. Lava, Nov 26 2008]

a(n) = 1100*a(n-1)-100000*a(n-2). G.f.: 10*x / ((100*x-1)*(1000*x-1)). [Colin Barker, Sep 16 2013]

EXAMPLE

n ...... a(n)

1 ....... 10

2 ...... 11000

3 ..... 11100000

4 .... 11110000000

5 ... 11111000000000

PROG

(PARI) Vec(10*x/((100*x-1)*(1000*x-1)) + O(x^100)) \\ Colin Barker, Sep 16 2013

CROSSREFS

Cf. A138118, A138145, A138146, A138147, A138719, A138720, A138721, A138722, A147538.

Sequence in context: A266872 A267705 A086164 * A138118 A267130 A267850

Adjacent sequences:  A138116 A138117 A138118 * A138120 A138121 A138122

KEYWORD

base,easy,nonn

AUTHOR

Omar E. Pol, Apr 03 2008

STATUS

approved

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Last modified April 19 04:19 EDT 2019. Contains 322237 sequences. (Running on oeis4.)