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 A242481 #6 Sep 08 2022 08:46:08 %S A242481 0,1,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,1,1,2,1,1,1,2,1,1,1,1,1,2,1,2, %T A242481 1,2,1,2,1,1,1,1,1,2,1,2,1,2,1,2,1,2,1,1,1,1,1,2,1,2,1,2,1,2,1,1,1,2, %U A242481 1,1,1,2,1,2,1,2,1,1,1,1,1,2,1,2,1,2,1 %N A242481 a(n) = ((n*(n+1)/2) mod n + sigma(n) mod n + antisigma(n) mod n) / n. %C A242481 a(1) = 0. If there is no odd multiply-perfect number then a(n) = 1 or 2 for n >= 2. See A242482 = numbers m such that a(n) = 1, A242483 = numbers m such that a(n) = 2. If there are any odd multiply-perfect numbers m > 1 then a(m) = 0. %H A242481 Jaroslav Krizek, <a href="/A242481/b242481.txt">Table of n, a(n) for n = 1..10000</a> %F A242481 a(n) = (A142150(n) + A054024(n) + A229110(n)) / n = ((A000217(n) mod n) + (A000203(n) mod n) + (A024816(n) mod n)) / n. %F A242481 a(n) = A242480(n) / n. %e A242481 a(8) = [(8*(8+1)/2) mod 8 + sigma(8) mod 8 + antisigma(8) mod 8] / 8 = (36 mod 8 + 15 mod 8 + 21 mod 8) / 8 = (4 + 7 + 5 ) / 8 = 2. %o A242481 (Magma) [((n*(n+1)div 2 mod n + SumOfDivisors(n) mod n + (n*(n+1)div 2-SumOfDivisors(n)) mod n))div n: n in [1..1000]] %Y A242481 Cf. A242480, A242482, A242483, A242484, A242485, A242486. %K A242481 nonn %O A242481 1,4 %A A242481 _Jaroslav Krizek_, May 16 2014