Number of permutations of [n] that avoid the shuffle pattern s-k-t, where s = 123 and t = 123.

A324137

Number of permutations of [n] that avoid the shuffle pattern s-k-t, where s = 123 and t = 123.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =120a(6) =720a(7) =5020a(8) =39790a(9) =352470a(10) =3445032a(11) =36775404a(12) =425282892a(13) =5292245764a(14) =70471602994a(15) =999394962306

External references