280816200

Appears in sequences

• a(n) = (2n+1)!/n!^2.at n=13A002457
• First numerator and then denominator of central elements of Leibniz's Harmonic Triangle.at n=27A046212
• Swinging factorial, a(n) = 2^(n-(n mod 2))*Product_{k=1..n} k^((-1)^(k+1)).at n=27A056040
• a(n) = n!/(k!)^2, where k is the largest number such that (k!)^2 divides n!.at n=26A056042
• a(n) = n * binomial(n-1, floor((n-1)/2)) = n * max_{i=0..n} binomial(n-1, i).at n=27A100071
• a(n) = 2^n*binomial((n + 1 + (n mod 2))/2, 1/2).at n=26A242172
• Lexicographically earliest sequence such that for any n>1, n=u*v, where u/v = a(n)/a(n-1) in reduced form.at n=26A260850
• 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=27A274707
• A260850 sorted into increasing order and duplicates omitted.at n=28A370974