Catafusenes (see reference for precise definition).

Terms

a(0) =0a(1) =0a(2) =1a(3) =7a(4) =31a(5) =139a(6) =609a(7) =2677a(8) =11827a(9) =52648a(10) =236071a(11) =1065774a(12) =4841428a(13) =22115678a(14) =101531221a(15) =468224323a(16) =2168076055a(17) =10076177264a(18) =46986612235a(19) =219777649588