4515840

Appears in sequences

• Expansion of e.g.f. 1/(1-2*x-2*x^2).at n=7A052611
• Product of numbers <= n that have a prime factor in common with n.at n=13A066570
• Matrix square of unsigned Lah triangle abs(A008297(n,k)) or A105278(n,k).at n=30A079621
• A triangular sequence based on expansion of the rational polynomial of A001788 as a Sheffer sequence: p(x,t)=Exp[x*t]*(-1/(2*t - 1)^3).at n=39A138192
• Irregular triangle T(n,k) = A096162(n,k) * A036040(n,k) * A048996(n,k) * A098546(n,k) * A178886(n,k), read by rows, 1 <= k <= A000041(n).at n=48A179236
• Triangle read by rows: T(n,k) is the coefficient of x^(2*k) in the cycle polynomial of the complete bipartite graph K_{n,n}, 1 <= k <= n.at n=32A291909
• Triangle T(n,k) read by rows: connected topologies of the effective potential in Goldstone diagrams with n interactions and k external potentials.at n=42A328924