OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..706
Index entries for linear recurrences with constant coefficients, signature (51,-650).
FORMULA
a(n) = 26^n - 26*25^(n - 1).
From Colin Barker, Nov 05 2015: (Start)
a(n) = 51*a(n-1) - 650*a(n-2) for n>2.
G.f.: 26*x^2 / ((1-25*x)*(1-26*x)). (End)
From G. C. Greubel, Sep 10 2021: (Start)
E.g.f.: exp(26*x) - (26/25)*exp(25*x). (End)
EXAMPLE
a(3) = 1326 because 26^3 - 26*(25^2) = 1326.
MATHEMATICA
Table[26*(26^(n-1) -25^(n-1)), {n, 25}] (* G. C. Greubel, Sep 10 2021 *)
PROG
(PARI) a(n) = 26^n - 26*(25^(n - 1)); \\ Michel Marcus, Aug 14 2013
(PARI) concat(0, Vec(26*x^2/((25*x-1)*(26*x-1)) + O(x^100))) \\ Colin Barker, Nov 05 2015
(Sage) [26*(26^(n-1) - 25^(n-1)) for n in (1..25)] # G. C. Greubel, Sep 10 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Luca Colucci, May 14 2005
EXTENSIONS
More terms from Michel Marcus, Aug 14 2013
STATUS
approved