A086948 a(n) = k where R(k+8) = 2.

12, 192, 1992, 19992, 199992, 1999992, 19999992, 199999992, 1999999992, 19999999992, 199999999992, 1999999999992, 19999999999992, 199999999999992, 1999999999999992, 19999999999999992, 199999999999999992, 1999999999999999992, 19999999999999999992, 199999999999999999992

Offset: 1

Author

Ray Chandler, Jul 24 2003

Keywords

• nonn
• base
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..300
• Index entries for linear recurrences with constant coefficients, signature (11,-10).

Crossrefs

Cf. A004086, A085331, A086947, A246057, A323639.

Programs

Magma

[2*(10^n-4): n in [1..25] ]; // Vincenzo Librandi, Aug 22 2011

Mathematica

Table[10*FromDigits[PadRight[{1},n,9]]+2,{n,20}] (* Harvey P. Dale, Dec 15 2017 *)

Formula

a(n) = 2*(10^n - 4).

R(a(n)) = A086947(n).

From Chai Wah Wu, Aug 01 2020: (Start)

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

G.f.: x*(60*x + 12)/((x - 1)*(10*x - 1)). (End)

From Elmo R. Oliveira, May 01 2025: (Start)

E.g.f.: 2*(3 - 4*exp(x) + exp(10*x)).

a(n) = 12*A246057(n-1) = 6*A323639(n). (End)