a(n) = (4*n)!/((2*n)!*(n)!) * (n/3)!/(4*n/3)!.
A347855
a(n) = (4*n)!/((2*n)!*(n)!) * (n/3)!/(4*n/3)!.
Terms
- a(0) =1a(1) =9a(2) =189a(3) =4620a(4) =120285a(5) =3241134a(6) =89237148a(7) =2493521172a(8) =70429218525
External references
- oeis: A347855
A347855
a(n) = (4*n)!/((2*n)!*(n)!) * (n/3)!/(4*n/3)!.