24725

Appears in sequences

• Number of permutations of length n which avoid the patterns 321, 2143, 3124; or avoid the patterns 132, 2314, 4312, etc.at n=42A116731
• a(n) = 1 + 4*n*(1 + 2*n^2)/3.at n=21A171272
• Number of decomposable fixed-point free involutions, also the number of disconnected chord diagrams with 2n nodes on an open string.at n=7A177797
• Number of integers in n-th generation of tree T(3^(-1/3)) defined in Comments.at n=56A274159
• Number of (binary) heaps of length n whose element set equals {1,2,3,4}.at n=7A376963
• Numbers k such that A075255(k) is the square of a prime.at n=20A386954