19835652870
domain: N
Appears in sequences
- a(n) = (2n+1)!/n!^2.at n=16A002457
- First numerator and then denominator of central elements of Leibniz's Harmonic Triangle.at n=33A046212
- Swinging factorial, a(n) = 2^(n-(n mod 2))*Product_{k=1..n} k^((-1)^(k+1)).at n=33A056040
- a(n) = n!/(k!)^2, where k is the largest number such that (k!)^2 divides n!.at n=32A056042
- a(n) = 20*C(2n,n)*(2n+1)/(n+4).at n=16A078820
- a(n) = 2^n*binomial((n + 1 + (n mod 2))/2, 1/2).at n=32A242172
- a(n) = A(n) if n is even else a(n) = A(n)*(n-1)/(n+1) with A(n) = ((n-1)!/ floor((n-1)/2)!^2).at n=33A274707
- Expansion of (1 + 2*x)/(1 + 4*x^2)^(3/2).at n=32A331552