OFFSET
0,2
COMMENTS
A transform of A000351 under the mapping mapping g(x)->(1/(1-x^3))g(x/(1-x^3)).
a(n) equals the number of n-length words on {0,1,2,3,4,5} such that 0 appears only in a run which length is a multiple of 3. - Milan Janjic, Feb 17 2015
LINKS
Milan Janjic, Binomial Coefficients and Enumeration of Restricted Words, Journal of Integer Sequences, 2016, Vol 19, #16.7.3
Index entries for linear recurrences with constant coefficients, signature (5,0,1).
FORMULA
a(n) = 5*a(n-1) + a(n-3).
a(n) = Sum_(k=0..floor(n/3)) binomial(n-2*k, k)*5^(n-3*k).
MATHEMATICA
CoefficientList[Series[1/(1-5x-x^3), {x, 0, 30}], x] (* or *) LinearRecurrence[ {5, 0, 1}, {1, 5, 25}, 30] (* Harvey P. Dale, May 08 2012 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Barry, Oct 20 2004
STATUS
approved