-a(n) is the greatest negative primitive root that all of the first n primes share.

Terms

a(0) =1a(1) =1a(2) =7a(3) =37a(4) =37a(5) =37a(6) =37a(7) =1423a(8) =10987a(9) =13297a(10) =219277a(11) =219277a(12) =669463a(13) =2215987a(14) =7841563a(15) =33376753a(16) =54444163a(17) =112545673a(18) =267625087a(19) =1676296087a(20) =2772262903a(21) =2782012963a(22) =4341199657a(23) =34694683237a(24) =39965586763a(25) =232265913427