416640

Appears in sequences

• Number of elements of order 4 in GL(n,2).at n=4A053875
• Smallest x such that sigma(x) = n*phi(x), or -1 if no such x exists.at n=16A055234
• Least balanced numbers (A020492): m such that the quotient sigma(m)/phi(m) equals the n-th prime.at n=6A063513
• Balanced refactorable numbers.at n=21A078543
• a(n) = n! * Sum_{d|n} (d/n)^d.at n=8A087905
• a(n) = Min{x : sigma(x) = n*phi(x), x is not a prime}, the least nonprime solutions to sigma(x) = n*phi(x); special balanced numbers.at n=16A088830
• Coefficients of series whose 8th power is the theta series of E_8 (see A004009).at n=3A108091
• Triangle read by rows, expansion of exp(x*exp(z)*tan(z)).at n=49A298213
• Triangle read by rows: T(n,k) is the number of direct sum decompositions of GF(2)^n whose maximal subspace has dimension k, 1<=k<=n, n>=1.at n=11A298399
• Dirichlet g.f.: (zeta(s-3) / zeta(s))^2.at n=39A338165
• Irregular triangular array read by rows. T(n,k) is the number of matrices in GL_n(F_2) having order k, 1<=k<=2^n-1, n>=1.at n=29A346743
• E.g.f. A(x) satisfies A(x) = 1 - (1/x^2) * log(1 - x^3*A(x)).at n=8A392960