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 A326143 #15 Dec 05 2023 08:12:34
%S A326143 -1,-1,-2,1,-4,0,-6,5,1,-2,-10,10,-12,-4,-6,13,-16,15,-18,12,-10,-8,
%T A326143 -22,30,1,-10,10,14,-28,12,-30,29,-18,-14,-22,49,-36,-16,-22,40,-40,
%U A326143 12,-42,18,18,-20,-46,70,1,33,-30,20,-52,60,-38,50,-34,-26,-58,78,-60,-28,20,61,-46,12,-66,24,-42,4,-70,117,-72,-34,34,26,-58,12
%N A326143 a(n) = A326142(n) - n, where A326142 gives the sum of all other divisors of n except its largest squarefree divisor.
%H A326143 Antti Karttunen, <a href="/A326143/b326143.txt">Table of n, a(n) for n = 1..20000</a>
%H A326143 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>.
%F A326143 a(n) = A326142(n) - n = (A000203(n)-A007947(n)) - n = A001065(n) - A007947(n).
%F A326143 a(n) = A066503(n) - A033879(n).
%F A326143 Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = A013661 - A065463 - 1 = -0.0595081... . - _Amiram Eldar_, Dec 05 2023
%t A326143 rad[n_] := Times @@ FactorInteger[n][[;; , 1]]; a[n_] := DivisorSigma[1, n] - rad[n] - n; Array[a, 100] (* _Amiram Eldar_, Dec 05 2023 *)
%o A326143 (PARI)
%o A326143 A007947(n) = factorback(factorint(n)[, 1]);
%o A326143 A326143(n) = (sigma(n)-A007947(n)-n);
%Y A326143 Cf. A000203, A001065, A007947, A033879, A066503, A326142, A326144.
%Y A326143 Cf. also A326054, A326127.
%Y A326143 Cf. A013661, A065463.
%K A326143 sign,easy
%O A326143 1,3
%A A326143 _Antti Karttunen_, Jun 09 2019