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 A336028 #23 Jan 29 2023 20:10:10 %S A336028 1,4,108,3306,7576,14502646,6247706232 %N A336028 The least k such that i*k + 1 is a product of i (not necessarily distinct) primes for i = 1, ..., n. %H A336028 Vladimir Letsko, <a href="https://www.facebook.com/notes/%D0%B7%D0%B0%D0%B4%D0%B0%D1%87%D0%B8-%D0%B8-math-problems-/%D0%BA%D0%BE%D0%BD%D0%BA%D1%83%D1%80%D1%81-2019-%D0%BA%D0%BE%D1%80%D0%BE%D1%82%D0%BA%D0%B8%D0%B5-%D0%B7%D0%B0%D0%B4%D0%B0%D1%87%D0%B8-%D1%81-%D1%80%D0%B5%D1%88%D0%B5%D0%BD%D0%B8%D1%8F%D0%BC%D0%B8/1398390813670090/">Problem K7</a> (in Russian). %e A336028 108 is in the sequence because 108 + 1 is prime, 2*108 + 1 is a product of 2 primes (7, 31), 3*108 + 1 is a product of 3 primes (5, 5, 13), and 108 is the least number with such properties. %p A336028 for kk to 6 do n := 1; %p A336028 do n := nextprime(n); f := true; %p A336028 for k from 2 to kk do a := ifactors(k*(n-1)+1)[2]; b := add(c[2], c in a); %p A336028 if b <> k then f := false; break end if end do; if f then print(n-1); break end if end do end do %o A336028 (PARI) is(k, n) = for(i=1, n, if(bigomega(i*k+1)!=i, return(1))); %o A336028 a(n) = for(k=1, oo, if(!is(k, n), return(k))); \\ _Jinyuan Wang_, Jul 08 2020 %Y A336028 Cf. A000005, A001222, A336027. %K A336028 nonn,more %O A336028 1,2 %A A336028 _Vladimir Letsko_, Jul 05 2020