144519domain: NAppears in sequencesNumber of permutations of length n which avoid the patterns 2143, 3124, 3421.at n=12A116761G.f.: exp( Sum_{n>=1} sigma(2n)*x^n/n ).at n=20A182818Number of nX5 0..1 arrays with every element equal to 0, 2, 3, 5, 6, 7 or 8 king-move adjacent elements, with upper left element zero.at n=7A300093