A178513 Partial sums of 80^n.

1, 81, 6481, 518481, 41478481, 3318278481, 265462278481, 21236982278481, 1698958582278481, 135916686582278481, 10873334926582278481, 869866794126582278481, 69589343530126582278481, 5567147482410126582278481, 445371798592810126582278481

Offset: 0

Author

Mark Dols, May 29 2010

Keywords

• nonn
• easy

Comments

Related to backward decimal expansion of fraction 1/79 and Pell numbers. [In which way? - Joerg Arndt, May 17 2011]

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..150
• Index entries for linear recurrences with constant coefficients, signature (81,-80).

Crossrefs

Cf. A000129, A021083, A038207, A178510, A178511, A178512.

Programs

Mathematica

Accumulate[80^Range[0,20]] (* Harvey P. Dale, Aug 11 2014 *)

Formula

a(n) = 80*a(n-1) + 1.

a(n) = (80^(n+1)-1)/79.

G.f.: 1/((1-80*x)*(1-x)).