-2865

Appears in sequences

• First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 121", based on the 5-celled von Neumann neighborhood.at n=31A270209
• a(n) = (n!)*2^(n-1)*mu_h(n) where mu_h is the hypergeometric Moebius function associated to the Dirichlet character modulo 4 h={1,0,-1,0,1,...} (see comment).at n=5A298510