a(n) = gcd(f(n), f(n+1)) where f(n) = n^4 + n^2 + 1.

Terms

a(0) =1a(1) =3a(2) =7a(3) =91a(4) =21a(5) =31a(6) =43a(7) =57a(8) =73a(9) =91a(10) =777a(11) =133a(12) =157a(13) =183a(14) =211a(15) =241a(16) =273a(17) =2149a(18) =343a(19) =381a(20) =421a(21) =463a(22) =507a(23) =553a(24) =4207a(25) =651a(26) =703a(27) =757a(28) =813a(29) =871