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 A054014 #10 Oct 27 2023 22:00:46 %S A054014 0,0,0,2,0,1,0,2,0,3,0,3,0,1,0,4,0,2,0,3,2,1,0,3,2,3,0,3,0,1,0,0,2,3, %T A054014 0,0,0,1,0,1,0,5,0,3,2,1,0,5,1,0,0,3,0,1,0,7,2,3,0,11,0,1,4,6,2,5,0,3, %U A054014 2,1,0,2,0,3,0,3,2,1,0,5,4,3,0,7,2,1,0,3,0,11,0,3,2,1,0,11,0,0,2,8,0,1,0 %N A054014 Chowla function of n read modulo (the number of divisors of n). %C A054014 Chowla's function (A048050) = sum of divisors of n except 1 and n. %H A054014 Antti Karttunen, <a href="/A054014/b054014.txt">Table of n, a(n) for n = 1..16384</a> %F A054014 a(n) = A048050(n) mod A000005(n). %p A054014 with(numtheory): [seq((sigma(i)-i-1) mod tau(i),i=1..120)]; %t A054014 Array[Mod[DivisorSigma[1, #] - # - 1, DivisorSigma[0, #]] &, 103] (* _Michael De Vlieger_, Oct 30 2017 *) %o A054014 (PARI) A054014(n) = ((sigma(n)-n-1) % numdiv(n)); \\ _Antti Karttunen_, Oct 30 2017 %Y A054014 Cf. A000005, A048050, A054013, A054015. %K A054014 nonn %O A054014 1,4 %A A054014 _Asher Auel_, Jan 17 2000