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 A328952 #13 Sep 08 2022 08:46:24 %S A328952 3,5,6,7,11,13,14,15,17,19,21,22,23,27,29,30,31,33,35,37,38,39,41,42, %T A328952 43,44,45,46,47,51,53,54,55,56,57,59,60,61,62,65,66,67,68,69,70,71,73, %U A328952 77,78,79,83,85,86,87,89,91,92,93,94,95,96,97,99,101,102 %N A328952 Arithmetic numbers (A003601) that are not antiharmonic (A020487). %C A328952 Numbers m such that the arithmetic mean of the divisors of m is an integer but the antiharmonic mean of the divisors of m is not an integer. %C A328952 Numbers m such that A(m) = A000203(m) / A000005(m) is an integer but B(m) = A001157(m) / A000203(m) is not an integer. %C A328952 Corresponding values of A(m): 2, 3, 3, 4, 6, 7, 6, 6, 9, 10, 8, 9, 12, 10, 15, 9, 16, 12, 12, 19, 15, 14, 21, 12, 22, ... %C A328952 Corresponding values of B(m): 5/2, 13/3, 25/6, 25/4, 61/6, 85/7, 125/12, 65/6, 145/9, 181/10, 125/8, ... %t A328952 Select[Range[100], Divisible[(sigma = DivisorSigma[1, #]), DivisorSigma[0, #]] && !Divisible[DivisorSigma[2, #], sigma] &] (* _Amiram Eldar_, Nov 17 2019 *) %o A328952 (Magma) [m: m in [1..10^5] | IsIntegral(SumOfDivisors(m) / NumberOfDivisors(m)) and not IsIntegral(&+[d^2: d in Divisors(m)] / SumOfDivisors(m))] %o A328952 (PARI) isok(m) = !(sigma(m) % numdiv(m)) && (sigma(m,2) % sigma(m)); \\ _Michel Marcus_, Nov 18 2019 %Y A328952 Complement of A277553 with respect to A003601. %Y A328952 Cf. A000005, A000203, A001157, A328953, A328954. %K A328952 nonn %O A328952 1,1 %A A328952 _Jaroslav Krizek_, Nov 17 2019