Largest prime factor of n!! + (n+1)!!.

Terms

a(0) =2a(1) =3a(2) =5a(3) =11a(4) =23a(5) =7a(6) =17a(7) =163a(8) =443a(9) =29a(10) =73a(11) =251a(12) =4027a(13) =2477a(14) =499a(15) =199a(16) =883a(17) =47a(18) =2671a(19) =308333a(20) =2099a(21) =859a(22) =510481a(23) =10429a(24) =514519a(25) =29629a(26) =51713a(27) =42337a(28) =5407a(29) =13841