21343

Appears in sequences

• a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-1)*a(1) for n >= 4.at n=11A025262
• Number of words of length n in a simple grammar.at n=10A056010
• Triangle T, read by rows, such that diagonal n equals column 0 of T^(n+1), the (n+1)-th matrix power of T.at n=50A098447
• E.g.f. satisfies: A(x) = exp(x*A(tan(x))).at n=6A141628
• Least number having exactly two odd prime factors that differ by 2*n^2.at n=38A190052
• Expansion of Product_{k>=1} (Product_{j=1..k} 1/(1 - x^(k*j))^j).at n=26A327066