19124

Appears in sequences

• a(n) = Sum_{d|n} rad(d)^(n/d), where rad(d) = A007947(d) is the squarefree kernel of d.at n=27A095001
• a(n) = n*(n^3 - n + 2)/2.at n=14A101374
• a(n) = least m such that sum of m reciprocal primes starting with n-th prime is >1.at n=22A137368
• Number of idempotent 3X3 0..n matrices.at n=37A222822
• Number of n X n 0..3 arrays of the sum of the corresponding element, the element to the east and the element to the south in a larger (n+1)X(n+1) 0..1 array.at n=2A229385
• Number of n X 3 0..3 arrays of the sum of the corresponding element, the element to the east and the element to the south in a larger (n+1) X 4 0..1 array.at n=2A229387
• T(n,k)=Number of nXk 0..3 arrays of the sum of the corresponding element, the element to the east and the element to the south in a larger (n+1)X(k+1) 0..1 array.at n=12A229392
• Consider n equally spaced points along a line and join every pair of points by a semicircle above the line; a(n) is the number of intersection points.at n=28A290447