OFFSET
1,2
COMMENTS
Column 5 of A224333.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
Index entries for linear recurrences with constant coefficients, signature (14,-61,84,-36).
FORMULA
a(n) = n*(2*6^(n-1) - 1).
a(n) = 14*a(n-1) - 61*a(n-2) + 84*a(n-3) - 36*a(n-4).
G.f.: x*(1 + 8*x - 34*x^2) / ((1 - x)^2*(1 - 6*x)^2). - Colin Barker, Aug 29 2018
EXAMPLE
Some solutions for n=3:
0 5 0 1 0 0 1 0 0 0 0 0 0 3 3 0 0 0 1 5 0
0 1 0 0 1 2 5 0 1 4 1 0 0 1 0 3 1 0 0 0 0
0 0 1 0 0 0 0 0 1 2 0 1 0 0 1 1 0 1 0 4 1
MATHEMATICA
Table[n*(2*6^(n-1)-1), {n, 1, 40}] (* or *)
CoefficientList[Series[(1 + 8*x - 34*x^2) / ((1 - x)^2*(1 - 6*x)^2), {x, 0, 40}], x] (* Stefano Spezia, Aug 29 2018 *)
PROG
(PARI) Vec(x*(1 + 8*x - 34*x^2) / ((1 - x)^2*(1 - 6*x)^2) + O(x^40)) \\ Colin Barker, Aug 29 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, formula from M. F. Hasler, William J. Keith and Rob Pratt in the Sequence Fans Mailing List, Apr 03 2013
STATUS
approved