Number of vertices in the n-th simplex graph of the complete graph on three vertices (K_3).

Terms

a(0) =3a(1) =8a(2) =21a(3) =54a(4) =140a(5) =365a(6) =954a(7) =2496a(8) =6533a(9) =17102a(10) =44772a(11) =117213a(12) =306866a(13) =803384a(14) =2103285a(15) =5506470a(16) =14416124a(17) =37741901a(18) =98809578a(19) =258686832a(20) =677250917a(21) =1773065918a(22) =4641946836a(23) =12152774589a(24) =31816376930a(25) =83296356200a(26) =218072691669a(27) =570921718806