472320

Appears in sequences

• Numbers n such that phi(n) * tau(n) divides n^2, but neither tau(n) nor phi(n) divides n.at n=26A287800
• a(n) is the least integer that can be expressed as the sum of one or more consecutive nonzero pentagonal numbers in exactly n ways.at n=2A334008
• Triangle read by rows: T(n, k) = (T(n-1, k-1) + T(n-1, k)) * 2 * n with initial values T(n, 0) = Sum_{i=0..n} (-1)^(n-i) * binomial(n, i) * A001147(i) and T(i, j) = 0 if j > i.at n=25A372260