a(n+1) = a(n) + n (if n is even), a(n+1) = a(n) * n (if n is odd).

Terms

a(0) =1a(1) =1a(2) =3a(3) =9a(4) =13a(5) =65a(6) =71a(7) =497a(8) =505a(9) =4545a(10) =4555a(11) =50105a(12) =50117a(13) =651521a(14) =651535a(15) =9773025a(16) =9773041a(17) =166141697a(18) =166141715a(19) =3156692585a(20) =3156692605a(21) =66290544705a(22) =66290544727