This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A321805 #35 Aug 19 2021 02:19:32
%S A321805 1,2,4,6,10,10,13,40,212,702,3531,19008,34858,39764,102312,47927,
%T A321805 94860,232006,658766,829583,1547703,2040211,32073218,51347260,
%U A321805 496226762,1504307318,16663026685,125080784519,241032642271,1216752358950,2147004248698,9320087810948,19383919945950,16259146126113,81023699301023,124167501991213
%N A321805 Number of permutations f of {1,...,n} such that k!*f(k) + 1 is prime for every k from 1 to n.
%C A321805 Though the first 27 terms are positive, we have a(50) = 0 since all the numbers 50!*k + 1, with k = 1..50, are composite.
%e A321805 a(2) = 2 since (1,2) and (2,1) are permutations of {1,2} with 1!*1 + 1 = 2, 2!*2 + 1 = 5, 1!*2 + 1 = 3 and 2!*1 + 1 = 3 all prime.
%t A321805 a[n_]:=a[n]=Permanent[Table[Boole[PrimeQ[i!*j+1]],{i,1,n},{j,1,n}]]; Do[Print[n," ",a[n]],{n,1,27}]
%o A321805 (PARI) a(n)={matpermanent(matrix(n, n, i, j, isprime(i!*j+1)))} \\ _Andrew Howroyd_, Nov 19 2018
%Y A321805 Cf. A000040, A000142, A231516, A231631, A321597, A321610, A321611, A321727, A321855.
%K A321805 nonn,more
%O A321805 1,2
%A A321805 _Zhi-Wei Sun_, Nov 19 2018
%E A321805 a(28)-a(31) from _Jinyuan Wang_, Jun 13 2020
%E A321805 a(32)-a(36) from _Vaclav Kotesovec_, Aug 19 2021