Number of catafusenes with 2n hexagons and D_{2h}(a) symmetry.

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =4a(5) =9a(6) =13a(7) =29a(8) =46a(9) =101a(10) =167a(11) =375a(12) =644a(13) =1461a(14) =2563a(15) =5899a(16) =10534a(17) =24469a(18) =44237a(19) =103643a(20) =189302a(21) =446381a(22) =821905a(23) =1948853a(24) =3612868a(25) =8605289a(26) =16044151a(27) =38362199a(28) =71877226a(29) =172423769