A002278 a(n) = 4*(10^n - 1)/9.

0, 4, 44, 444, 4444, 44444, 444444, 4444444, 44444444, 444444444, 4444444444, 44444444444, 444444444444, 4444444444444, 44444444444444, 444444444444444, 4444444444444444, 44444444444444444, 444444444444444444, 4444444444444444444, 44444444444444444444, 444444444444444444444

Offset

0,2

Links

Ivan Panchenko, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (11,-10).

Formula

a(n) = A075415(n)/A002283(n). - Reinhard Zumkeller, May 31 2010

From Vincenzo Librandi, Jul 22 2010: (Start)

a(n) = a(n-1) + 4*10^(n-1) with a(0)=0;

a(n) = 11*a(n-1) - 10*a(n-2) with a(0)=0, a(1)=4. (End)

G.f.: 4*x/((1 - x)*(1 - 10*x)). - Ilya Gutkovskiy, Feb 24 2017

E.g.f.: 4*exp(x)*(exp(9*x) - 1)/9. - Stefano Spezia, Sep 13 2023

a(n) = A007091(A024049(n)). - Michel Marcus, Jun 16 2024

Mathematica

LinearRecurrence[{11, -10}, {0, 4}, 20] (* Robert G. Wilson v, Jul 06 2013 *)

Prog

(PARI) a(n)=4*(10^n-1)/9 \\ Charles R Greathouse IV, Sep 24 2015

Crossrefs

Cf. A002275, A002276, A002277, A002279, A002280, A002281, A002282, A002283, A075415, A178632.

Cf. A007091, A024049.

Sequence in context: A216272 A221405 A105038 * A112897 A163013 A087813

Adjacent sequences: A002275 A002276 A002277 * A002279 A002280 A002281

Keyword

easy,nonn

Author

N. J. A. Sloane

Status

approved