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 A358396 #10 Nov 17 2022 14:12:24 %S A358396 104,134,164,314,404,494,524,554,566,584,674,692,734,764,854,944,974, %T A358396 1124,1154,1196,1214,1304,1322,1364,1394,1484,1574,1682,1724,1754, %U A358396 1784,1814,1826,1844,1994,2024,2144,2204,2384,2414,2456,2474,2564,2624,2654,2804,2834,3002 %N A358396 Even numbers k such that sigma(k) + sigma(k+2) < 2*sigma(k+1); even terms in A053229. %C A358396 Even numbers k such that A053223(k) < 0. %H A358396 Jianing Song, <a href="/A358396/b358396.txt">Table of n, a(n) for n = 1..20000</a> %e A358396 104 is a term since sigma(105) = 192 is greater than the average of sigma(104) = 210 and sigma(106) = 162. %o A358396 (PARI) isA358396(n) = !(n%2) && (sigma(n) + sigma(n+2) < 2*sigma(n+1)) %Y A358396 Cf. A053229, A053223, A000203 (sigma), A358395. %K A358396 nonn %O A358396 1,1 %A A358396 _Jianing Song_, Nov 13 2022