G.f.: (1-x)^9/((1-5*x+6*x^2-4*x^3+x^4)*(-1+4*x-3*x^2+x^3)*(1-3*x+x^2)*(-1+2*x)).
A089947
G.f.: (1-x)^9/((1-5*x+6*x^2-4*x^3+x^4)*(-1+4*x-3*x^2+x^3)*(1-3*x+x^2)*(-1+2*x)).
Terms
- a(0) =1a(1) =5a(2) =25a(3) =115a(4) =500a(5) =2092a(6) =8512a(7) =33910a(8) =132892a(9) =514079a(10) =1968021a(11) =7470434a(12) =28160354a(13) =105542777a(14) =393672627a(15) =1462503264a(16) =5414896000a(17) =19991387639a(18) =73628208598a(19) =270614786791a(20) =992880076249
External references
- oeis: A089947