Number of permutations of length n containing exactly 2 occurrences of 1243.
A224181
Number of permutations of length n containing exactly 2 occurrences of 1243.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =0a(4) =4a(5) =56a(6) =543a(7) =4600a(8) =36691a(9) =284370a(10) =2174352a(11) =16533360a(12) =125572259a(13) =955035260a(14) =7283925999a(15) =55755366698a(16) =428521485446
External references
- oeis: A224181