17990600

Appears in sequences

• Solution to the Dancing School Problem with 9 girls and n+9 boys: f(9,n).at n=8A079914
• Solution to the Dancing School Problem with n girls and n+8 boys: f(n,8).at n=8A079927
• E.g.f.: REVERT(2*x/(1+exp(x))) = Sum_{n>=0} a(n)*x^n/n!.at n=10A088789
• Number of ways to place k nonattacking anassas on an n X n chess board. Triangle T(n,k) read by rows.at n=54A378561