a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-3*k-1,n-3*k).
A371771
a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-3*k-1,n-3*k).
Terms
- a(0) =1a(1) =3a(2) =21a(3) =166a(4) =1377a(5) =11748a(6) =102088a(7) =898677a(8) =7987305a(9) =71517307a(10) =644134026a(11) =5829345492a(12) =52964836184a(13) =482846377185
External references
- oeis: A371771