a(n) = Sum_{k=0..n} C(n,k)^2*C(n-k,k), where C(n,k) denotes the binomial coefficient n!/(k!*(n-k)!).
A275027
a(n) = Sum_{k=0..n} C(n,k)^2*C(n-k,k), where C(n,k) denotes the binomial coefficient n!/(k!*(n-k)!).
Terms
- a(0) =1a(1) =1a(2) =5a(3) =19a(4) =85a(5) =401a(6) =1931a(7) =9605a(8) =48469a(9) =248365a(10) =1286605a(11) =6726875a(12) =35441275a(13) =187935775a(14) =1002122525a(15) =5369287019a(16) =28889315669a(17) =156015203845a(18) =845330354321
External references
- oeis: A275027