Number of permutations in S_{n+2} containing an increasing subsequence of length n.

Terms

a(0) =2a(1) =6a(2) =23a(3) =78a(4) =207a(5) =458a(6) =891a(7) =1578a(8) =2603a(9) =4062a(10) =6063a(11) =8726a(12) =12183a(13) =16578a(14) =22067a(15) =28818a(16) =37011a(17) =46838a(18) =58503a(19) =72222a(20) =88223a(21) =106746a(22) =128043a(23) =152378a(24) =180027a(25) =211278a(26) =246431a(27) =285798a(28) =329703a(29) =378482