34040

Appears in sequences

• Number of graphs with n nodes and floor(n(n-1)/4) edges.at n=8A000717
• Numbers that are the least element of a k-cycle (k > 1) of permutation A113821.at n=25A115641
• a(n) = (9*n+4)*(9*n+5).at n=20A177073
• Number of ordered triples (w,x,y) with all terms in {1,...,n} and 2w<x+y.at n=40A182260
• Number of simple unlabeled graphs with n nodes and n(n-1)/4 edges.at n=8A218113
• Numbers x such that sigma(x)=sigma(T(x)), where sigma(x) is the sum of the divisors of x and T(x) the transform defined in A243993.at n=16A245468
• a(n) = A008412(n-1) + A008412(n-2) for n>1, a(0)=0, a(1)=1.at n=20A287324
• a(0) = a(1) = 1; a(n) = [x^n] Product_{k=1..n-1} (1 + x^a(k))/(1 - x^a(k)).at n=54A296387
• Greatest integer whose square root is less than or equal to Sum_{j=0..n} sqrt(j).at n=42A338277
• Numbers k such that sigma(k) = psi(k) + tau(k) + omega(k)^7.at n=3A392385