20421

Appears in sequences

• Numbers k such that k^3 divides 17^(k^2) + 1.at n=21A177817
• Floor((9n+1/n)^n).at n=2A197598
• a(n) = round((9*n+1/n)^n).at n=2A197982
• Number of 3 X 3 0..n symmetric arrays with all rows summing to floor(n*3/2).at n=34A213801
• G.f.: Product_{k>=1} (1+x^k)^(2*k+1).at n=12A255834
• Sum of numbers in the n-th antidiagonal of the reciprocity array of 1.at n=43A259577
• Numbers n such that n*prime(n) is a pandigital number containing digits 0-9 exactly once.at n=5A272552
• a(n) = Sum_{k=0..n} n^k * binomial(k+n,k).at n=4A368489
• a(n) = floor(8*n^3/27).at n=41A379852