13063680

Appears in sequences

• a(n) = n! * C(n,2).at n=7A001804
• a(n) = (1/2) * (number of n X n 0..2 matrices M with MM' mod 3 = I, where M' is the transpose of M and I is the n X n identity matrix).at n=5A071302
• Triangular sequence based on the coefficients of the Blaschke product like tan(3u) polynomial function: p(x,t)=Exp[x*t]*(-t)*(3 - t^2)/(-1 + 3*t^2).at n=39A137436
• Number of ways to form k labeled groups, each with a distinct leader, using n people. Triangle T(n,k) = n!*k^(n-k)/(n-k)! for 1 <= k <= n.at n=41A199673
• Number of permutations of n>1 having exactly 3 points P on the boundary of their bounding square.at n=9A208528
• Triangular array read by rows: T(n,k) is the number of endofunctions, functions f:{1,2,...,n}->{1,2,...,n}, that have exactly k elements with no preimage; n>=0, 0<=k<=n.at n=46A219859
• Sum of the cumulative sums of all the permutations of divisors of number n.at n=29A246916
• O.g.f. A(x,y) satisfies: [x^n] exp( n * x*A(x,y) ) * (n + y - A(x,y)) = 0 for n > 0.at n=53A305109
• a(n) is the smallest number which can be represented as the product of n distinct integers > 1 in exactly n ways.at n=8A360590
• Expansion of e.g.f. A(x,y) satisfying A(x,y) = 1 + x*A(x,y) * exp(x*y * A(x,y)), as a triangle read by rows.at n=46A366230
• Expansion of e.g.f. 1/(1 - (exp(x^3) - 1)/x^2)^2.at n=9A375812
• Triangle read by rows: T(n,m) (1<=m<=n) = number of surjections f:[n]->[m] with f(n) != f(j), j<n.at n=53A380977