The number of permutations of length n sortable by 3 prefix reversals (in the pancake sorting sense).

A228398

The number of permutations of length n sortable by 3 prefix reversals (in the pancake sorting sense).

Terms

    a(0) =1a(1) =2a(2) =6a(3) =21a(4) =52a(5) =105a(6) =186a(7) =301a(8) =456a(9) =657a(10) =910a(11) =1221a(12) =1596a(13) =2041a(14) =2562a(15) =3165a(16) =3856a(17) =4641a(18) =5526a(19) =6517a(20) =7620a(21) =8841a(22) =10186a(23) =11661a(24) =13272a(25) =15025a(26) =16926a(27) =18981a(28) =21196a(29) =23577

External references