1270080

Appears in sequences

• a(n) = denominator of Sum_{k=1..n} 1/k^2.at n=9A007407
• Expansion of e.g.f.: x^2*log(1-x)^4.at n=9A052790
• Triangle T(n,k) read by rows: number of labeled trees with n nodes and k leaves, n >= 2, 2 <= k <= n.at n=29A055314
• Number of labeled trees with n nodes and 3 leaves.at n=5A055315
• Numbers n such that the squarefree kernel of n is equal to the number of divisors of n.at n=34A070226
• Seventh column of triangle A075501.at n=3A075920
• a(n) = (A000108(n)^2)*(n+1)!.at n=5A089835
• Number of permutations of (1,3,5,7,9,...,2n-1) where every adjacent pair in the permutation are coprime.at n=9A107761
• Denominators of row sums of rational triangle A120072/A120073.at n=8A120077
• Triangle read by rows: G(s, rho) = ((s-1)!/s)*Sum_{i=0..s-1} ((s-i)/i!)*(s*rho)^i.at n=38A122525
• Triangular sequence from coefficients of the umbral calculus expansion of a Golden -Mean Bernoulli function(A001898): p(x,t)=t*phi^(x*t)/(phi^t - 1), where the golden ratio replaces "e".at n=33A137524
• Triangle read by rows: T(n, k) = [x^k]( (n+2)!*(3*EulerE(n, x+1) - EulerE(n, x))/4 ).at n=34A166553
• Sum of the sizes of the normalizers of all prime order cyclic subgroups of the alternating group A_n.at n=8A181967
• As p runs through the primes, sequence gives denominator of Sum_{k=1..p-1} 1/k^2.at n=4A186720
• Product of cumulative sums of divisors of n.at n=43A197410
• Triangular array read by rows: T(n,k) is the number of inversion pairs ( p(i) < p(j) with i>j ) that are separated by exactly k elements in all n-permutations (where the permutation is represented in one line notation); n>=2, 0<=k<=n-2.at n=29A202363
• a(n) = v(n+1)/v(n), where v=A203518.at n=4A203519
• Triangular array read by rows. T(n,k) is the number of functional digraphs on {1,2,...,n} such that no node is at a distance greater than one from a cycle and there are k recurrent elements whose preimage contains only one element, n>=0, 0<=k<=n.at n=51A220222
• Denominators of coefficients in series expansion of Cl_2(x)+x*log(x), where Cl_2 is the Clausen function of order 2.at n=7A249700
• Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum equal to the antidiagonal sum or central row sum equal to the central column sum.at n=8A258918