A177769 a(n) = 111*n.

111, 222, 333, 444, 555, 666, 777, 888, 999, 1110, 1221, 1332, 1443, 1554, 1665, 1776, 1887, 1998, 2109, 2220, 2331, 2442, 2553, 2664, 2775, 2886, 2997, 3108, 3219, 3330, 3441, 3552, 3663, 3774, 3885, 3996, 4107, 4218, 4329, 4440, 4551, 4662, 4773, 4884, 4995, 5106

Offset: 1

Author

Paul Curtz, May 13 2010

Keywords

• nonn
• easy

Comments

The reference contains also sequences A102807, A109344, A075415, and A109492.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000
• Émile Fourrey, Le nombre 37, Récreations arithmétiques, 1899 and later, Vuibert, Paris, page 11.
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

Cf. A075415, A102807, A109344, A109492.

Programs

Magma

[111*n: n in [1..50]]; // Vincenzo Librandi, Aug 04 2011

Formula

G.f.: 111*x/(x-1)^2.

a(n) = 2*a(n-1) - a(n-2).

a(n) = a(n-1) + 111.

E.g.f.: 111*x*exp(x). - Stefano Spezia, Sep 15 2023