a(n) = A059896(A260443(n), A260443(1+n)).

Terms

a(0) =2a(1) =6a(2) =6a(3) =30a(4) =90a(5) =270a(6) =30a(7) =210a(8) =630a(9) =6750a(10) =6750a(11) =1890a(12) =15750a(13) =47250a(14) =210a(15) =2310a(16) =6930a(17) =47250a(18) =47250a(19) =330750a(20) =992250a(21) =425250a(22) =47250a(23) =103950a(24) =173250a(25) =2315250a(26) =2315250a(27) =519750a(28) =8489250a(29) =25467750