A138119 Concatenation of n digits 1 and 2*n-1 digits 0.

10, 11000, 11100000, 11110000000, 11111000000000, 11111100000000000, 11111110000000000000, 11111111000000000000000, 11111111100000000000000000, 11111111110000000000000000000, 11111111111000000000000000000000, 11111111111100000000000000000000000

Offset

1,1

Comments

a(n) has 3*n-1 digits.

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

Links

Table of n, a(n) for n=1..12.

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

Formula

From Colin Barker, Sep 16 2013: (Start)

a(n) = 1100*a(n-1) - 100000*a(n-2).

G.f.: 10*x / ((100*x-1)*(1000*x-1)). (End)

Example

n ...... a(n)
1 ....... 10
2 ...... 11000
3 ..... 11100000
4 .... 11110000000
5 ... 11111000000000

Mathematica

LinearRecurrence[{1100, -100000}, {10, 11000}, 15] (* Paolo Xausa, Feb 06 2024 *)

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 * A327233 A138118 A267130

Adjacent sequences: A138116 A138117 A138118 * A138120 A138121 A138122

Keyword

base,easy,nonn

Author

Omar E. Pol, Apr 03 2008

Status

approved