Sort then Add, a(1)=21.

Terms

a(0) =21a(1) =33a(2) =66a(3) =132a(4) =255a(5) =510a(6) =525a(7) =780a(8) =858a(9) =1446a(10) =2892a(11) =5181a(12) =6339a(13) =9708a(14) =10497a(15) =11976a(16) =23655a(17) =47211a(18) =58458a(19) =104046a(20) =105492a(21) =117951a(22) =229530a(23) =251889a(24) =377778a(25) =755556a(26) =1311123a(27) =2422356a(28) =4645812a(29) =5890380