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 A359666 #61 Aug 01 2023 10:55:53 %S A359666 1,13,61,73,133,145,193,205,253,397,457,481,493,553,565,613,625,661, %T A359666 673,733,757,793,817,853,913,973,997,1033,1093,1213,1237,1285,1321, %U A359666 1333,1453,1513,1537,1633,1645,1657,1681,1813,1825,1873,1933,2077,2113,2173,2233,2245,2293,2413,2497 %N A359666 Integers k such that sigma(k) <= sigma(k+1) <= sigma(k+2) <= sigma(k+3), where sigma is the sum of divisors. %H A359666 Seiichi Manyama, <a href="/A359666/b359666.txt">Table of n, a(n) for n = 1..10000</a> %e A359666 73 is a term because sigma(73)=74 <= sigma(74)=114 <= sigma(75)=124 <= sigma(76)=140. %t A359666 Position[OrderedQ /@ Partition[DivisorSigma[1, Range[2500]], 4, 1], True] // Flatten (* _Amiram Eldar_, Feb 28 2023 *) %o A359666 (PARI) isok(n)=sigma(n)<=sigma(n+1) && sigma(n+1)<=sigma(n+2) && sigma(n+2)<=sigma(n+3) %Y A359666 Cf. A000203, A053224, A323726, A364662. %K A359666 nonn,easy %O A359666 1,2 %A A359666 _Alexandru Petrescu_, Feb 28 2023