OFFSET
1,13
COMMENTS
The number of multinomial coefficients such that multinomial(t_1+t_2+..._+t_n,t_1,t_2,...,t_n)=7 and t_1+2*t_2+...+n*t_n=n, where t_1, t_2, ... , t_n are nonnegative integers.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,1,1,0,0,0,0,0,-1).
FORMULA
a(n) = floor((n-1)*(1/6))+floor((n-1)*(1/7))-floor((1/7)*n).
G.f.: x^8*(2*x^5+x^4+x^3+x^2+x+1) / ((x-1)^2*(x+1)*(x^2-x+1)*(x^2+x+1)*(x^6+x^5+x^4+x^3+x^2+x+1)). - Colin Barker, Oct 14 2013
EXAMPLE
The number 19 has three partitions such that a(19)=3: 1+1+1+1+1+1+13, 1+3+3+3+3+3+3 and 2+2+2+2+2+2+7.
MAPLE
seq(floor((n-1)*(1/6))+floor((n-1)*(1/7))-floor((1/7)*n), n=1..75)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mircea Merca, Oct 11 2013
STATUS
approved