A173806 a(n) = (7*10^n - 61)/9 for n > 0.

1, 71, 771, 7771, 77771, 777771, 7777771, 77777771, 777777771, 7777777771, 77777777771, 777777777771, 7777777777771, 77777777777771, 777777777777771, 7777777777777771, 77777777777777771, 777777777777777771, 7777777777777777771, 77777777777777777771, 777777777777777777771

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

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

Formula

a(n) = 10*a(n-1) + 61 with n > 0, a(0)=-6.

From Vincenzo Librandi, Jul 05 2012: (Start)

G.f.: x*(1+60*x)/((1-x)*(1-10*x)).

a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)

E.g.f.: 6 + exp(x)*(7*exp(9*x) - 61)/9. - Elmo R. Oliveira, Sep 09 2024

Mathematica

CoefficientList[Series[(1+60*x)/((1-x)*(1-10*x)), {x, 0, 30}], x] (* Vincenzo Librandi, Jul 05 2012 *)

Prog

(Magma)[(7*10^n-61)/9: n in [1..20]]; // Vincenzo Librandi, Jul 05 2012

Crossrefs

Cf. A093176.

Sequence in context: A351896 A089706 A220623 * A253683 A210699 A346023

Adjacent sequences: A173803 A173804 A173805 * A173807 A173808 A173809

Keyword

nonn,easy

Author

Vincenzo Librandi, Feb 25 2010

Status

approved