20997

Appears in sequences

• Number of asymmetric monoids (semigroups with identity) of order n.at n=6A058130
• L-th order palindromes with L > 2.at n=11A089381
• X-toothpick sequence on Z^3 lattice (see Comments for precise definition).at n=38A160170
• Numbers k such that A(k+1) = A(k) + 1, where A() = A005101() are the abundant numbers.at n=23A169822
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 324", based on the 5-celled von Neumann neighborhood.at n=45A271257
• a(n) is the number of edges formed by n-secting the angles of a nonagon (enneagon).at n=25A335783