OFFSET
4,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 4..1000
Wikipedia, Partition of a set
Index entries for linear recurrences with constant coefficients, signature (1,18,-18,-127,127,450,-450,-844,844,792,-792,-288,288)
FORMULA
G.f.: (72*x^11 -84*x^10 -258*x^9 +60*x^8 +287*x^7 +29*x^6 -141*x^5 -34*x^4 +33*x^3 +10*x^2 -3*x-1) *x^4 / ((2*x+1) *(2*x-1) *(x+1) *(6*x^2-1) *(3*x^2-1) *(x-1)^2 *(2*x^2-1)^2).
EXAMPLE
a(5) = 4: 12|3|4|5, 1|23|4|5, 1|2|34|5, 1|2|3|45.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Jun 10 2018
STATUS
approved