If a, b in sequence, so is ab+5.

Terms

a(0) =2a(1) =9a(2) =23a(3) =51a(4) =86a(5) =107a(6) =177a(7) =212a(8) =219a(9) =359a(10) =429a(11) =443a(12) =464a(13) =534a(14) =723a(15) =779a(16) =863a(17) =891a(18) =933a(19) =968a(20) =1073a(21) =1178a(22) =1451a(23) =1563a(24) =1598a(25) =1731a(26) =1787a(27) =1871a(28) =1913a(29) =1941