195840

Appears in sequences

• Triangular sequence of coefficients from the expansion of p(x,t)=Tan(x*t)/Tan(t).at n=19A137660
• Number of (w,x,y,z) with all terms in {1,...,n} and w>=2x and y<=3z.at n=31A212521
• Govindarajan's triangle beta arising in enumeration of multi-dimensional partitions, read by rows.at n=36A216808
• Number x such that x | A255242(x).at n=37A255243
• Numbers n such that phi(n) * tau(n) divides n^2, but neither tau(n) nor phi(n) divides n.at n=17A287800
• Solutions x of uphi(x)/x = 2/3, where uphi is the unitary phi function (A047994).at n=9A305678
• Numbers m with a divisor d such that tau(d) * sigma(d) = m.at n=22A331668
• Numbers k such that A051378(k) > 2*k and A333926(k) <= 2*k.at n=4A349284
• Draw a regular n-gon and the enclosing circle, then for each pair of vertices X, Y, draw a circle with diameter XY; the union of these figures is the graph H_n; sequence gives number of edges in H_n.at n=29A370979
• a(n) = Sum_{k=0..floor(n/3)} (k+1) * 2^k * 3^(n-3*k) * binomial(k,2*(n-3*k)).at n=24A391960