Number of permutations of length n which avoid the patterns 1234, 1432, 2341.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =72a(5) =232a(6) =717a(7) =2157a(8) =6370a(9) =18557a(10) =53490a(11) =152868a(12) =433781a(13) =1223511a(14) =3433182a(15) =9590277a(16) =26683932a(17) =73986112a(18) =204501885a(19) =563677377a(20) =1549776250a(21) =4251231533a(22) =11637412806a(23) =31795910076a(24) =86721532517a(25) =236147429547