A099669 Partial sums of repdigits of A002276.

2, 24, 246, 2468, 24690, 246912, 2469134, 24691356, 246913578, 2469135800, 24691358022, 246913580244, 2469135802466, 24691358024688, 246913580246910, 2469135802469132, 24691358024691354, 246913580246913576, 2469135802469135798, 24691358024691358020, 246913580246913580242

Offset: 1

Author

Labos Elemer, Nov 17 2004

Keywords

• base
• nonn
• easy

Examples

			2 + 22 + 222 + 2222 = a(4) = 2468.
		

Links

• Matthew House, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (12,-21,10).

Crossrefs

Cf. A002275-A002283, A014824, A057932.

Programs

Maple

A099669:=n->(2/81)*(10^(n+1) - 9*n - 10): seq(A099669(n), n=1..30); # Wesley Ivan Hurt, Apr 18 2017

Mathematica

<Robert G. Wilson v, Nov 20 2004 *)
LinearRecurrence[{12,-21,10},{2,24,246},30] (* Harvey P. Dale, Jun 01 2025 *)

Formula

a(n) = (2/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004

a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3). - Matthew House, Jun 30 2016

G.f.: 2*x/((1 - x)^2*(1 - 10*x)). - Ilya Gutkovskiy, Jun 30 2016

From Elmo R. Oliveira, Apr 02 2025: (Start)

E.g.f.: 2*exp(x)*(10*exp(9*x) - 9*x - 10)/81.

a(n) = 2*A014824(n). (End)