55516

Appears in sequences

• Number of (n+1)X(n+1) 0..2 symmetric matrices with every 2X2 subblock having one or two distinct values, and new values 0..2 introduced in lower triangle row major order.at n=3A210855
• Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 105", based on the 5-celled von Neumann neighborhood.at n=7A270161
• Number of permutations p of [n] such that at most one element of {p(1),...,p(i-1)} is between p(i) and p(i+1) for all i < n and n = 0 or p(n) < 3.at n=12A356832