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A190542
7^n - 4^n.
2
0, 3, 33, 279, 2145, 15783, 113553, 807159, 5699265, 40091463, 281426673, 1973132439, 13824509985, 96821901543, 677954637393, 4746487768119, 33228635602305, 232613334118023, 1628344878433713, 11398620307466199
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
FORMULA
a(n) = 11*a(n-1) -28*a(n-2).
a(n) = A000420(n) - A000302(n). - Michel Marcus, Feb 26 2014
MAPLE
A190542:=n->7^n - 4^n; seq(A190542(n), n=0..30); # Wesley Ivan Hurt, Feb 26 2014
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
Sequence in context: A206950 A189644 A003129 * A180416 A043038 A274264
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jun 02 2011
STATUS
approved