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 A295301 #22 Sep 08 2022 08:46:20 %S A295301 0,0,1,-2,3,2,3,0,-3,4,7,0,7,6,7,-14,11,-6,11,8,5,10,15,8,-5,14,11,4, %T A295301 21,6,15,-4,17,16,19,-36,19,22,15,16,29,10,23,20,21,22,31,-12,13,-10, %U A295301 27,10,35,22,31,24,25,34,43,12,31,30,15,-62,41,18,35,32,37,22,47,-24,37,38,15,28,45,30,47,20 %N A295301 a(n) = n - phi(sigma(n)), where phi = A000010 and sigma = A000203. %H A295301 Antti Karttunen, <a href="/A295301/b295301.txt">Table of n, a(n) for n = 1..32768</a> %F A295301 a(n) = n - A062401(n). %p A295301 with(numtheory): seq(n-phi(sigma(n)),n=1..80); # _Muniru A Asiru_, Jan 02 2019 %t A295301 Array[# - EulerPhi@ DivisorSigma[1, #] &, 80] (* _Michael De Vlieger_, Jan 01 2019 *) %o A295301 (PARI) A295301(n) = (n - eulerphi(sigma(n))); %o A295301 (Magma) [n-EulerPhi(SumOfDivisors(n)):n in [1..100]]; // _Marius A. Burtea_, Jan 01 2019 %o A295301 (GAP) a:=List([1..80],n->n-Phi(Sigma(n)));; Print(a); # _Muniru A Asiru_, Jan 02 2019 %Y A295301 Cf. A000010, A000203, A062401, A295303. %Y A295301 Cf. A001229 (positions of zeros), A066694 (of negative terms). %Y A295301 Cf. also A295302, A295305. %K A295301 sign %O A295301 1,4 %A A295301 _Antti Karttunen_, Nov 21 2017