OFFSET
0,2
COMMENTS
Length-n words from letters {1,2,...,7} with at least one letter greater than 4. - Joerg Arndt, Jun 02 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..300
Index entries for linear recurrences with constant coefficients, signature (11,-28).
FORMULA
a(n) = 11*a(n-1) -28*a(n-2).
MAPLE
MATHEMATICA
Table[7^n - 4^n, {n, 0, 30}] (* Wesley Ivan Hurt, Feb 26 2014 *)
LinearRecurrence[{11, -28}, {0, 3}, 20] (* Harvey P. Dale, Dec 21 2019 *)
PROG
(Magma) [7^n -4^n: n in [0..30]];
(PARI) a(n)=7^n-4^n \\ Charles R Greathouse IV, Jun 02 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jun 02 2011
STATUS
approved