Number of alkyls C_{n+15} H_{2n+10} (Phenan) with n carbon atoms.

Terms

a(0) =1a(1) =5a(2) =30a(3) =115a(4) =425a(5) =1396a(6) =4440a(7) =13470a(8) =40000a(9) =116140a(10) =332827a(11) =942435a(12) =2647450a(13) =7386925a(14) =20511620a(15) =56731383a(16) =156451985a(17) =430462915a(18) =1182341890a(19) =3243215495a(20) =8887664047a(21) =24338341165a(22) =66616422775a(23) =182276901760a(24) =498657609720