Number of n-step self-avoiding cycles on the hypertriangular lattice.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =0a(5) =5a(6) =30a(7) =77a(8) =192a(9) =879a(10) =3860a(11) =14102a(12) =52916a(13) =217295a(14) =896252a(15) =3631970a(16) =14862624a(17) =61811422a(18) =258539856a(19) =1084119347a(20) =4568946800a(21) =19360675922