The number of partitions of [n] with exactly 2 blocks without peaks.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =8a(5) =15a(6) =27a(7) =48a(8) =85a(9) =150a(10) =264a(11) =464a(12) =815a(13) =1431a(14) =2512a(15) =4409a(16) =7738a(17) =13580a(18) =23832a(19) =41823a(20) =73395a(21) =128800a(22) =226029a(23) =396654a(24) =696080a(25) =1221536a(26) =2143647a(27) =3761839a(28) =6601568a(29) =11584945