A134230 a(n) = (10^n+1)^2-1.

3, 120, 10200, 1002000, 100020000, 10000200000, 1000002000000, 100000020000000, 10000000200000000, 1000000002000000000, 100000000020000000000, 10000000000200000000000, 1000000000002000000000000, 100000000000020000000000000, 10000000000000200000000000000

Offset: 0

Author

Enoch Haga, Oct 14 2007

Keywords

• easy
• nonn

Comments

Previous name was: -1 + Sum of first 10^n + 1 odd numbers.

Links

• Colin Barker, Table of n, a(n) for n = 0..499
• Index entries for linear recurrences with constant coefficients, signature (110,-1000).

Crossrefs

Cf. A134228, A134229.

Programs

Mathematica

LinearRecurrence[{110,-1000},{3,120},15] (* or *) CoefficientList[Series[-3*(70*x-1) / ((10*x-1)*(100*x-1)),{x,0,14}],x] (* James C. McMahon, Apr 05 2025 *)

PARI

Vec(-3*(70*x-1)/((10*x-1)*(100*x-1))  + O(x^100)) \\ Colin Barker, Jan 27 2015

Formula

a(n) = (10^n+1)^2-1. - N. J. A. Sloane, Oct 15 2007

a(n) = 110*a(n-1)-1000*a(n-2). - Colin Barker, Jan 27 2015

G.f.: -3*(70*x-1) / ((10*x-1)*(100*x-1)). - Colin Barker, Jan 27 2015

Extensions

Edited by N. J. A. Sloane, Oct 15 2007

Offset and name corrected by Arkadiusz Wesolowski, Jun 12 2013

New name (using formula by N. J. A. Sloane) from Joerg Arndt, Jan 27 2015