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 A202779 #24 Oct 13 2015 12:36:08
%S A202779 8,3,4,1410,6,154770,5246010,2894220,407874180,214580145780,
%T A202779 9448481062020,247236503934420,2545206711847800,18178612369988250180,
%U A202779 53792264108455702830
%N A202779 Least k such that x*k - 1 produces primes for x=1..n and composite for x=n+1.
%D A202779 Wacław Sierpiński, Czym sie zajmuje teoria liczb. Warsaw: PW "Wiedza Powszechna", 1957, pp. 88-89.
%t A202779 Table[k = 3; While[i = 1; While[i <= n && PrimeQ[i*k - 1], i++]; i <= n || PrimeQ[i*k - 1], k++]; k, {n, 8}]
%Y A202779 Another version of A088651.
%K A202779 more,nonn
%O A202779 1,1
%A A202779 _Arkadiusz Wesolowski_, Jan 06 2012