1181737

Appears in sequences

• a(n) = Sum_{i=0..n} (n!/(n-i)!)^2.at n=6A006040
• a(2n-1) = n*a(2n-2), a(2n) = n*a(2n-1) + 1.at n=11A007876
• T(n,k)=Number of nXk array permutations with each element remaining in its original row or its original column.at n=22A188808
• T(n,k)=Number of nXk array permutations with each element remaining in its original row or its original column.at n=26A188808
• Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) = (n!)^k * Sum_{j=1..n} (1/j!)^k.at n=42A343863
• a(n) is the numerator of Sum_{k=0..n} 1 / (k!)^2.at n=6A354302
• Interleaving A006040 and A228229.at n=11A375231