a(n) is the smallest prime x such that x^2-n! is also prime.

Terms

a(0) =2a(1) =2a(2) =3a(3) =11a(4) =19a(5) =31a(6) =79a(7) =211a(8) =607a(9) =1931a(10) =6337a(11) =21961a(12) =78919a(13) =295291a(14) =1143563a(15) =4574149a(16) =18859777a(17) =80014843a(18) =348776611a(19) =1559776279a(20) =7147792903a(21) =33526120129a(22) =160785623729a(23) =787685471519