Number of paraffins C_n H_{2n-1} XYZ with n carbon atoms.

Terms

a(0) =0a(1) =1a(2) =4a(3) =13a(4) =42a(5) =131a(6) =402a(7) =1218a(8) =3657a(9) =10899a(10) =32298a(11) =95257a(12) =279844a(13) =819390a(14) =2392392a(15) =6967956a(16) =20250974a(17) =58744089a(18) =170118980a(19) =491913999a(20) =1420493862a(21) =4096940530a(22) =11803172152a(23) =33970257473a(24) =97678027311a(25) =280624328431a(26) =805587723862