131241domain: NAppears in sequencesNumber of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 11000-01110-00011 pattern in any orientation.at n=19A147189O.g.f. satisfies A^6(z) = 1/(1 - z)*( BINOMIAL(BINOMIAL(A(z))) )^5.at n=4A258381