OFFSET
1,2
REFERENCES
E. Mathieu, Mémoire sur le nombre de valeurs que peut acquérir une fonction quand on y permute ses variables de toutes les manières possibles, Journ. de math. (2) 5 (1860), 9-42 (see p. 39).
LINKS
Ronald P. Nordgren, Compound Lucas Magic Squares, arXiv:2103.04774 [math.GM], 2021. See Table 2 p. 12.
Index entries for linear recurrences with constant coefficients, signature (30,-81).
FORMULA
a(n) = 3^(n-1)*(3^(2*n - 2) - 1)/2.
From Colin Barker, Sep 02 2013: (Start)
a(n) = 30*a(n-1) - 81*a(n-2).
G.f.: 12*x^2 / ((3*x-1)*(27*x-1)). (End)
MATHEMATICA
Table[3^(x - 1) (3^(2 x - 2) - 1)/2, {x, 1, 15}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Aug 04 2007
EXTENSIONS
More terms from Colin Barker, Sep 02 2013
STATUS
approved