Number of positive braids with n crossings of 5 strands.

Terms

a(0) =1a(1) =4a(2) =13a(3) =37a(4) =99a(5) =254a(6) =636a(7) =1567a(8) =3822a(9) =9261a(10) =22346a(11) =53773a(12) =129174a(13) =309958a(14) =743228a(15) =1781330a(16) =4268166a(17) =10224885a(18) =24492034a(19) =58662298a(20) =140498877a(21) =336491169a(22) =805872377a(23) =1929983778a(24) =4622083068a(25) =11069289411a(26) =26509431448a(27) =63486333364