656208domain: NAppears in sequencesNumber of nonoverlapping placements of one 1 X 1 square and one 2 X 2 square on an n X n board.at n=28A173963Vassiliev invariant of fourth order for the torus knots.at n=31A180324v(n+1)/v(n), where v=A203583.at n=3A203584Numbers k that divide the base-5 reversal of k.at n=33A222816