47850

Appears in sequences

• Number of singular 2 X 2 matrices over Z(n) (i.e., with determinant = 0).at n=29A020478
• Poincaré series [or Poincare series] P(T_{6,2}; x).at n=11A124618
• A partition product of Stirling_2 type [parameter k = 5] with biggest-part statistic (triangle read by rows).at n=17A157405
• Number of set partitions of [n] into exactly three blocks where sizes of distinct blocks are coprime.at n=9A280881
• Unitary practical numbers that are nonsquarefree.at n=37A287173
• a(n) = Sum_{1 <= x_1, x_2 <= n} sigma( n/gcd(x_1, x_2, n) ).at n=29A373129