a(n) = Sum_{i+j+k=n, 0<=j<=i<=n, 0<=k<=n} (n+k)!/(i! * j! * (2*k)!).
A092465
a(n) = Sum_{i+j+k=n, 0<=j<=i<=n, 0<=k<=n} (n+k)!/(i! * j! * (2*k)!).
Terms
- a(0) =1a(1) =2a(2) =7a(3) =28a(4) =104a(5) =415a(6) =1631a(7) =6438a(8) =25557a(9) =101320a(10) =402620a(11) =1600973a(12) =6369850a(13) =25362023a(14) =101021833a(15) =402558824a(16) =1604694342a(17) =6398518221a(18) =25519847999a(19) =101805661146a(20) =406209454697
External references
- oeis: A092465