229881

Appears in sequences

• 4-dimensional pyramidal numbers: a(n) = (3*n+1)*binomial(n+2, 3)/4. Also Stirling2(n+2, n).at n=36A001296
• a(n) is the number of free polyominoes of width 4 and size n.at n=10A354850
• Irregular triangle read by rows: T(n,k) is the number of free polyominoes with n cells and width k, n >= 1, 1 <= k <= ceiling(n/2).at n=52A379623