Number of permutations of [ n ] with exactly one 132-pattern and two 123-patterns.

Terms

a(0) =1a(1) =4a(2) =14a(3) =47a(4) =152a(5) =472a(6) =1408a(7) =4048a(8) =11264a(9) =30464a(10) =80384a(11) =207616a(12) =526336a(13) =1312768a(14) =3227648a(15) =7835648a(16) =18808832a(17) =44695552a(18) =105250816a(19) =245825536a(20) =569901056a(21) =1312292864a(22) =3003121664a(23) =6833569792a(24) =15468593152a(25) =34846277632a(26) =78148272128a(27) =174533378048a(28) =388291887104