Number of 231-avoiding stabilized-interval-free permutations of size n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =6a(6) =18a(7) =54a(8) =170a(9) =551a(10) =1817a(11) =6092a(12) =20722a(13) =71325a(14) =248055a(15) =870402a(16) =3077861a(17) =10959008a(18) =39261382a(19) =141430953a(20) =512002865a(21) =1861872379a(22) =6798330676a(23) =24915934639a(24) =91630864177a(25) =338048560865