Number of Apollonian packings of n circles that are Eulerian and irreducible.

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =2a(5) =1a(6) =5a(7) =3a(8) =18a(9) =19a(10) =79a(11) =134a(12) =501a(13) =1147a(14) =3976a(15) =11055a(16) =37231a(17) =114560a(18) =384053a(19) =1244056a(20) =4193857a(21) =13977946a(22) =47522279a(23) =161222224a(24) =553033544a(25) =1899744032a(26) =6571595339a(27) =22793047258a(28) =79449718217a(29) =277760027418