OFFSET
0,2
COMMENTS
A record in a word a_1,a_2,...,a_n is a letter a_j that is larger than all the preceding letters. That is, a_j>a_i for all i<j.
LINKS
Index entries for linear recurrences with constant coefficients, signature (6,-11,6).
FORMULA
O.g.f.: x*(-3 + 6*x - 2*x^2)/(-1 + 6*x - 11*x^2 + 6*x^3) = d/dy A(x,y)|y=1 where A(x,y) is the o.g.f. for A285852.
a(n) = Sum_{k=0..3} A285852(n,k)*k.
a(n) = 11/2*3^(n-1)-2^n-1/2, n>0. - R. J. Mathar, Aug 19 2022
MATHEMATICA
nn = 25; Range[0, nn]!; CoefficientList[Series[D[Product[1 + v z/(1 - j z), {j, 1, 3}], v] /. v -> 1, {z, 0, nn}], z]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Geoffrey Critzer, Jul 18 2020
STATUS
approved