2640993domain: NAppears in sequencesSum of binomial(n,k) over squarefree k.at n=21A245268Number of n X n 0..1 arrays with each 1 adjacent to 1, 3 or 5 king-move neighboring 1's.at n=5A296945Number of nX6 0..1 arrays with each 1 adjacent to 1, 3 or 5 king-move neighboring 1s.at n=5A296950