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 A288654 #7 Mar 04 2018 10:35:43
%S A288654 -3,0,0,4,0,5,0,12,6,7,0,15,0,9,8,28,0,20,0,21,10,13,0,35,10,15,24,27,
%T A288654 0,0,0,60,14,19,12,54,0,21,16,49,0,0,0,39,32,25,0,75,14,42,20,45,0,65,
%U A288654 16,63,22,31,0,0,0,33,40,124,18,0,0,57,26,0,0,122
%N A288654 a(n) = (sigma(n)-n-1)*(3-omega(n)).
%C A288654 If n is prime, then a(n) = 0. If n is semiprime, then a(n) = sopfr(n).
%H A288654 Antti Karttunen, <a href="/A288654/b288654.txt">Table of n, a(n) for n = 1..65537</a>
%t A288654 Table[(DivisorSigma[1, n] - n - 1) (3 - PrimeNu[n]), {n, 100}]
%o A288654 (PARI) A288654(n) = ((sigma(n)-n-1)*(3-omega(n))); \\ _Antti Karttunen_, Mar 04 2018
%Y A288654 Cf. A000203 (sigma), A001221 (omega), A001414 (sopfr), A048050 (Chowla's function).
%K A288654 sign,easy
%O A288654 1,1
%A A288654 _Wesley Ivan Hurt_, Jun 12 2017