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 A296203 #17 Jul 09 2025 04:46:18
%S A296203 1,2,5,4,7,10,9,8,9,22,13,20,15,18,27,16,19,34,21,60,45,42,25,40,25,
%T A296203 38,37,36,31,78,33,32,57,38,63,108,39,42,51,120,43,90,45,116,95,82,49,
%U A296203 80,49,86,95,76,55,122,67,72,65,70,61,204,63,66,65,64,93,130,69,76,125,166,73,184,75,86,125,180,101,190,81,240,81
%N A296203 Xor-Moebius transform of A000203, the sum of divisors.
%C A296203 Unique sequence satisfying SumXOR_{d divides n} a(d) = sigma(n) for all n > 0, where SumXOR is the analog of summation under the binary XOR operation. See A295901 for a list of some of the properties of Xor-Moebius transform.
%H A296203 Antti Karttunen, <a href="/A296203/b296203.txt">Table of n, a(n) for n = 1..16384</a>
%H A296203 Rémy Sigrist, <a href="/A295901/a295901_1.png">Scatterplot of the first 2^16 terms</a>
%o A296203 (PARI) A296203(n) = { my(v=0); fordiv(n, d, if(issquarefree(n/d), v=bitxor(v, sigma(d)))); (v); } \\ after code in A295901.
%Y A296203 Cf. A000203, A169813, A256739, A295901, A296208.
%K A296203 nonn
%O A296203 1,2
%A A296203 _Antti Karttunen_, Dec 25 2017, from _Rémy Sigrist_'s "gallery of scatter plots" in A295901