122809domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/2)} T(n-k,k), T given by A026769.at n=21A026779Base 7 digits are, in order, the first n terms of the periodic sequence with initial period 1,0,2.at n=6A037500Parent nodes of nonzero terms of A262509: a(n) = A049820(A262509(n)).at n=30A262510