Number of permutations of [n] having exactly two adjacent 3-cycles.

A370528

Number of permutations of [n] having exactly two adjacent 3-cycles.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =3a(8) =12a(9) =57a(10) =348a(11) =2460a(12) =19806a(13) =178950a(14) =1794420a(15) =19778210a(16) =237696420a(17) =3093642300a(18) =43350548655a(19) =650733622665

External references