Analog of A060410 for the 7x+1 problem (cf. A133421).

Terms

a(0) =8a(1) =50a(2) =162a(3) =470a(4) =9584a(5) =28400a(6) =91890a(7) =193040a(8) =265070a(9) =291824a(10) =337100a(11) =388830a(12) =524070a(13) =3231824a(14) =18052070a(15) =30949850a(16) =31021880a(17) =65552768a(18) =774659600a(19) =10276607888a(20) =38128783428a(21) =190067750300