Number of path change-ringing sequences of length n for 4 bells.

Terms

a(0) =1a(1) =4a(2) =12a(3) =30a(4) =72a(5) =186a(6) =464a(7) =1122a(8) =2646a(9) =6050a(10) =13408a(11) =28726a(12) =58844a(13) =114418a(14) =209176a(15) =355926a(16) =559108a(17) =800636a(18) =1014616a(19) =1086948a(20) =930728a(21) =595740a(22) =256688a(23) =58948