331520

Appears in sequences

• Specific heat coefficients for square lattice spin 2 Ising model.at n=32A010112
• Numbers j such that sigma(sigma(j)) = k*j for some k.at n=41A019278
• Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (2,9)-perfect numbers.at n=2A019286
• Numerators of e.g.f.: -cot(arctanh(x)), odd powers only.at n=4A102064
• Triangle: r=23;l=7;m(r,l,n)=(r - l)*IdentityMatrix[n] + l*Table[1, {i, 1, n}, {j, 1, n}].at n=32A157981
• Numbers n such that denominator(sigma(sigma(n))/n) = denominator(sigma(sigma(s))/s) where s = sigma(n).at n=23A275321
• Sheffer triangle S2[4,1] = (exp(x), exp(4*x) - 1).at n=25A285061
• Subsequence of terms of A019278 whose sum of divisors is also a term of A019278.at n=15A292949
• Number of non-unitary square divisors of n!.at n=48A375188