OFFSET
1,2
COMMENTS
Companion sequence = A030192 beginning (1, 6, 30, 144, 684,...).
LINKS
FORMULA
a(n) = 6*a(n-1) - 6*a(n-2); a(1) = 1, a(2) = 5.
Term (1,1) of M^n, where M = the 3x3 matrix [1,1,1; 1,2,1; 3,1,3].
a(n) = Sum_{1<=k<=n} A030523(n,k)*2^(k-1). - Philippe Deléham, Feb 19 2013
EXAMPLE
a(5) = 540 = 6*a(4) - 6*a(3) = 6*(114) - 6*24.
a(5) = 540 = term (1,1) of X^5.
MATHEMATICA
LinearRecurrence[{6, -6}, {1, 5}, 30] (* Harvey P. Dale, Oct 01 2014 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson and Roger L. Bagula, May 28 2008
EXTENSIONS
More terms from R. J. Mathar, May 31 2008
More terms from Harvey P. Dale, Oct 01 2014
STATUS
approved