A071009 Number of solutions (x,y,z,u,v,w) to x+y+z = u+v+w, 0<=x,y,z,u,v,w<=n-1, x>=y>=z, u>=v>=w.

1, 4, 16, 48, 119, 256, 500, 900, 1525, 2456, 3796, 5664, 8207, 11588, 16004, 21672, 28845, 37800, 48856, 62356, 78691, 98280, 121592, 149128, 181445, 219132, 262840, 313256, 371131, 437256, 512492, 597740, 693977, 802224, 923580

Offset

1,2

Links

Table of n, a(n) for n=1..35.

Formula

Recurrence: a(n) = 3*a(n-1)-a(n-2)-4*a(n-3)+2*a(n-4)+2*a(n-5)+2*a(n-6)-4*a(n-7)-a(n-8)+3*a(n-9)-a(n-10). G.f.: x*(1+x+5*x^2+8*x^3+5*x^4+x^5+x^6)/(1+x+x^2)/(1+x)^2/(1-x)^6.

Crossrefs

Cf. A071816.

Sequence in context: A100625 A203248 A223839 * A210066 A131126 A159964

Adjacent sequences: A071006 A071007 A071008 * A071010 A071011 A071012

Keyword

nonn

Author

Vladeta Jovovic, Jun 10 2002

Status

approved