Number of permutations of length n which avoid the patterns 123, 51432.

Terms

a(0) =1a(1) =2a(2) =5a(3) =14a(4) =41a(5) =119a(6) =336a(7) =924a(8) =2492a(9) =6636a(10) =17536a(11) =46137a(12) =121095a(13) =317434a(14) =831571a(15) =2177734a(16) =5702191a(17) =14929519a(18) =39087182a(19) =102332996a(20) =267912946a(21) =701407172a(22) =1836310110a(23) =4807524929a(24) =12586266701a(25) =32951277474a(26) =86267568321a(27) =225851430414a(28) =591286726197