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 A353543 #10 Apr 26 2022 04:52:15 %S A353543 4,6,10,14,45,63,75,105,165,195,231,242,255,285,286,345,374,418,435, %T A353543 442,465,494,506,598,638,646,682,754,782,806,814,874,902,946,962,1034, %U A353543 1066,1118,1166,1222,1287,1298,1342,1378,1474,1562,1606,1683,1738,1826,1881 %N A353543 Primitive terms of A353537. %C A353543 If a number is in A353537 then all its multiples are in it. Therefore, the terms of A353537 whose proper divisors are not in A353537 are the primitive terms. %H A353543 Amiram Eldar, <a href="/A353543/b353543.txt">Table of n, a(n) for n = 1..10000</a> %e A353543 4 is a term since sigma(4)/4 = 7/4 = 1.75 > Pi^2/6 = 1.644..., the proper divisors of 4 are 1 and 2, sigma(1)/1 = 1 < Pi^2/6 and sigma(2)/2 = 3/2 < Pi^2/6. %t A353543 q[n_] := DivisorSigma[-1, n] > Pi^2/6 && AllTrue[Most @ Divisors[n], DivisorSigma[-1, #] < Pi^2/6 &]; Select[Range[2000], q] %Y A353543 Cf. A000203, A013661, A353537. %Y A353543 Subsequences: A071395, A091191, A353544. %K A353543 nonn %O A353543 1,1 %A A353543 _Amiram Eldar_, Apr 25 2022