Number of permutations of length n containing exactly 2 occurrences of 123 and 2 occurrences of 132.

A224288

Number of permutations of length n containing exactly 2 occurrences of 123 and 2 occurrences of 132.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =6a(6) =26a(7) =94a(8) =306a(9) =934a(10) =2732a(11) =7752a(12) =21488a(13) =58432a(14) =156288a(15) =411904a(16) =1071104a(17) =2750976a(18) =6984704a(19) =17545216a(20) =43634688a(21) =107511808a(22) =262602752a(23) =636223488a(24) =1529741312a(25) =3652059136a(26) =8660975616a(27) =20412104704a(28) =47826599936a(29) =111446851584

External references