19768

Appears in sequences

• G.f.: -1 + Product_{k>=1} (1 + prime(k)*x^prime(k)).at n=36A002099
• Number of polyhexes of class PF2 with a particular symmetry.at n=9A030529
• Dirichlet convolution of b_n=1 with c_n=3^(n-1).at n=9A034730
• Denominators of convergents to Pi by Farey fractions.at n=42A063673
• Coefficient of x^5 in (1-x-x^2)^(-n).at n=13A139798
• Sum of the numerators for computing the third moment of the probability mass function for probability of k pairs among the involutions on n elements (A000085) assuming equal likelihood.at n=7A174774
• Numbers n such that both n*Pi and n*e are within 1/sqrt(n) of integers.at n=38A208530
• Number T(n,k) of endofunctions f on [n] that are self-inverse on [k]; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=31A245348
• a(n) = Sum_{d|n} d^Omega(d).at n=26A344459
• a(n) = Sum_{d|n} d^(tau(d) - 1).at n=26A348349