20115

Appears in sequences

• Numbers k such that phi(k)+sigma(k) is a perfect cube.at n=13A061366
• Numbers k such that the number of primes <= k is equal to the sum of primes from the smallest prime factor of k to the largest prime factor of k.at n=8A074210
• Numbers n such that n + sum of prime factors of n = (n+1) + sum of prime factors of (n+1).at n=20A075654
• Number of partitions of n into lower Wythoff numbers (A000201).at n=56A192184
• Deficient numbers n having a companion m > n such that sigma(n)/n = sigma(m)/m.at n=35A212608
• Petersen graph (3,1) coloring a rectangular array: number of n X 3 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal, diagonal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0.at n=3A223499
• T(n,k)=Petersen graph (3,1) coloring a rectangular array: number of nXk 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal, diagonal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0.at n=18A223504
• Petersen graph (3,1) coloring a rectangular array: number of 4Xn 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal, diagonal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0.at n=2A223507