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A177769
a(n) = 111*n.
2
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
1,1
COMMENTS
The reference contains also sequences A102807, A109344, A075415, and A109492.
LINKS
Émile Fourrey, Le nombre 37, Récreations arithmétiques, 1899 and later, Vuibert, Paris, page 11.
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
PROG
(Magma) [111*n: n in [1..50]]; // Vincenzo Librandi, Aug 04 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, May 13 2010
STATUS
approved