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 A362778 #10 Jun 25 2023 01:02:57 %S A362778 2,3,5,7,13,19,5,7,73,97,11,241,19,13,601,7,11,2161,43,13,29,71,17, %T A362778 15121,20161,11,30241,35281,61,11,73,161281,449,241921,282241,47,19, %U A362778 293,1088641,1451521,23,2177281,13,2903041,17,11,13,10886401,233,18144001,17,101,29030401,32659201,43 %N A362778 Triangular array read by rows: T(n,k) is the least prime factor of n!*k + 1, n >= 1, 1 <= k <= n. %C A362778 The primes in each row are distinct because n!*k + 1 are coprime for 1 <= k <= n, and hence this array gives a simple proof that there are infinitely many prime numbers. %F A362778 T(n,k) = A020639(A362777(n,k)). %e A362778 Triangle T(n,k) begins: %e A362778 n\k 1 2 3 4 5 6 ... %e A362778 1 2 %e A362778 2 3 5 %e A362778 3 7 13 19 %e A362778 4 5 7 73 97 %e A362778 5 11 241 19 13 601 %e A362778 6 7 11 2161 43 13 29 %e A362778 ... %Y A362778 Cf. A362777, A362779. %Y A362778 Cf. A051301 (1st column). %K A362778 tabl,nonn %O A362778 1,1 %A A362778 _Joe B. Stephen_, May 03 2023