The number of simple permutations of length n in a particular geometric grid class.

Terms

a(0) =1a(1) =2a(2) =0a(3) =2a(4) =3a(5) =7a(6) =13a(7) =25a(8) =46a(9) =84a(10) =151a(11) =269a(12) =475a(13) =833a(14) =1452a(15) =2518a(16) =4347a(17) =7475a(18) =12809a(19) =21881a(20) =37274a(21) =63336a(22) =107375a(23) =181657a(24) =306743a(25) =517057a(26) =870168a(27) =1462250a(28) =2453811a(29) =4112479