Number of permutations of length n which avoid the patterns 213, 51432.

Terms

a(0) =1a(1) =2a(2) =5a(3) =14a(4) =41a(5) =121a(6) =356a(7) =1044a(8) =3057a(9) =8948a(10) =26192a(11) =76674a(12) =224465a(13) =657137a(14) =1923817a(15) =5632105a(16) =16488346a(17) =48270655a(18) =141315320a(19) =413709331a(20) =1211159679a(21) =3545745012a(22) =10380388294a(23) =30389230117a(24) =88966354626a(25) =260454516946a(26) =762496740130