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 A381739 #9 Mar 06 2025 01:45:38
%S A381739 6,10,14,44,52,68,76,92,105,116,124,286,296,328,344,374,376,418,424,
%T A381739 442,472,488,495,506,536,568,584,585,632,664,712,776,808,824,856,872,
%U A381739 904,1016,2096,2145,2192,2224,2384,2416,2512,2608,2672,2768,2805,2864,2896,3056
%N A381739 Number k such that k^2 is abundant, and d^2 is nonabundant for any proper divisor d of k.
%C A381739 The primitive terms of A381738. Each term of A381738 is a multiple of a term in this sequence.
%H A381739 Amiram Eldar, <a href="/A381739/b381739.txt">Table of n, a(n) for n = 1..10000</a>
%t A381739 q[k_] := DivisorSigma[-1, k^2] > 2 && AllTrue[Divisors[k], DivisorSigma[-1, #^2] <= 2 || # == k &]; Select[Range[3200], q]
%o A381739 (PARI) is1(k) = {my(f = factor(k)); prod(i = 1, #f~, f[i,2] *= 2); sigma(f, -1) > 2;}
%o A381739 isok(k) = if(!is1(k), 0, fordiv(k, d, if(d < k && is1(d), return(0))); 1);
%Y A381739 Subsequence of A381738.
%Y A381739 A381741 is a subsequence.
%Y A381739 Cf. A005101, A263837.
%K A381739 nonn,easy
%O A381739 1,1
%A A381739 _Amiram Eldar_, Mar 05 2025