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 A087273 #22 Sep 08 2022 08:45:11
%S A087273 7,5,2,11,17,5,13,29,7,11,47,7,31,13,71,5,89,23,101,107,11,17,5,67,73,
%T A087273 19,31,23,41,17,191,197,103,19,7,227,59,7,251,13,269,17,41,29,37,23,
%U A087273 317,67,31,43,7,359,181,29,193,79,101,37,13,211,17,11,461,467,47,17,71,23
%N A087273 Largest prime factor of 3*prime(n) + 1.
%C A087273 a(n) >= 5 except for n = 3. - _Robert Israel_, Sep 19 2016
%H A087273 Harvey P. Dale, <a href="/A087273/b087273.txt">Table of n, a(n) for n = 1..1000</a>
%F A087273 a(n) = A006530(1 + 3*A000040(n)).
%e A087273 n=100: p(100)=541, m = 3*541 + 1 = 1624 = 2*2*2*7*29 so a(100)=29.
%p A087273 seq(max(numtheory:-factorset(3*ithprime(i)+1)),i=1..100); # _Robert Israel_, Sep 19 2016
%t A087273 ffi[x_] := Flatten[FactorInteger[x]] ma[x_] := Part[Reverse[ffi[x]], 2] Table[ma[3*Prime[w]+1], {w, 1, 100}]
%t A087273 Table[FactorInteger[3Prime[n]+1][[-1,1]],{n,70}] (* _Harvey P. Dale_, Apr 10 2012 *)
%o A087273 (PARI) a(n) = vecmax(factor(3*prime(n)+1)[,1]); \\ _Michel Marcus_, Sep 19 2016
%o A087273 (Magma) [#f eq 0 select 1 else f[#f][1] where f is Factorization(3*NthPrime(n)+1): n in [1..90]]; // _Vincenzo Librandi_, Sep 20 2016
%Y A087273 Cf. A006530.
%K A087273 nonn
%O A087273 1,1
%A A087273 _Labos Elemer_, Sep 18 2003