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 A072341 #9 Nov 07 2017 18:30:31
%S A072341 1,2,1,4,1,1,2,2,4,1,1,1,2,3,3,10,1,2,2,1,3,1,3,1,10,1,1,2,1,1,3,2,2,
%T A072341 2,2,6,5,1,2,2,1,1,2,4,1,1,2,3,4,4,1,2,2,2,1,2,3,2,1,2,5,1,3,4,4,3,2,
%U A072341 1,1,3,1,6,2,2,3,2,1,2,3,2,6,1,4,2,1,3,2,1,2,4,1,2,2,3,2,3,2,12,1,6,1,2,3
%N A072341 a(n) = the least natural number k such that k*sigma(n) + 1 is prime.
%C A072341 Conjecture: a(n) is less than or equal to n for all n.
%H A072341 Antti Karttunen, <a href="/A072341/b072341.txt">Table of n, a(n) for n = 1..16384</a>
%F A072341 a(n) = A034693(A000203(n)). - _Antti Karttunen_, Nov 07 2017
%e A072341 sigma(4) = 7 and the least natural number k such that 7 k + 1 is prime is k = 4; so a(4) = 4.
%t A072341 f[n_] := Module[{i}, i = 0; While[ ! PrimeQ[i*DivisorSigma[1, n] + 1], i++ ]; i]; Table[f[i], {i, 1, 150}]
%o A072341 (PARI) A072341(n) = { my(k=1,s=sigma(n)); while(!isprime(1+(k*s)),k++); k; }; \\ _Antti Karttunen_, Nov 07 2017
%Y A072341 Cf. A000203, A034693, A034694, A072344.
%K A072341 nonn
%O A072341 1,2
%A A072341 _Joseph L. Pe_, Jul 16 2002