a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-k+1,n-3*k).
A371775
a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-k+1,n-3*k).
Terms
- a(0) =1a(1) =5a(2) =36a(3) =287a(4) =2396a(5) =20539a(6) =179125a(7) =1581282a(8) =14085997a(9) =126357958a(10) =1139825257a(11) =10328791996a(12) =93951594230a(13) =857328996139
External references
- oeis: A371775