a(1) = 31, a(n) = prime(a(n-1)) - 3a(n-1).

Terms

a(0) =31a(1) =34a(2) =37a(3) =46a(4) =61a(5) =100a(6) =241a(7) =800a(8) =3733a(9) =23824a(10) =200777a(11) =2159228a(12) =28739455a(13) =461652916a(14) =8767088533a(15) =193511261098