Number of permutations tau of {1,...,n} such that k^4 + tau(k)^4 is prime for every k = 1,...,n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =4a(5) =4a(6) =4a(7) =64a(8) =16a(9) =144a(10) =144a(11) =0a(12) =144a(13) =144a(14) =289a(15) =4356a(16) =2916a(17) =22500a(18) =79524a(19) =1887876a(20) =313600a(21) =3459600a(22) =2985984a(23) =50069776a(24) =32353344a(25) =2056803904a(26) =237591396a(27) =11713732900a(28) =10265337124a(29) =342040164964