Number of permutations of [n] with exactly 2 valleys which avoid the permutation 1324.

A099745

Number of permutations of [n] with exactly 2 valleys which avoid the permutation 1324.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =12a(5) =168a(6) =1409a(7) =9187a(8) =51362a(9) =258674a(10) =1207855a(11) =5326205a(12) =22459080a(13) =91368900a(14) =360977373a(15) =1391835607a(16) =5257593566a(17) =19515948358a(18) =71358739003a(19) =257521313441a(20) =918732810340

External references