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 A144715 #5 Jun 02 2025 00:35:41 %S A144715 275,431,587,1115,1271,2309,2891,3203,3725,4421,4787,5453,6017,6257, %T A144715 6599,6797,7295,7841,8507,8735,8975,9233,9557,9983,10733,11327,11939, %U A144715 12875,13031,13439,14285,15113,15383,15665,16307,17129,17849,18461 %N A144715 A144325(n) + A144313(n) + A144315(n). %C A144715 All terms are congruent to 5 modulo 6: A144325(n) and A144313(n) are each congruent to 5 and A144315(n) is congruent to 1. %C A144715 None of the given terms have more than three distinct prime factors and most have only two. Several are primes. %C A144715 The multiples of five are all fifth figurate numbers corresponding to polygons having a number of sides k = floor(a(n) / 10) + 2. 3725 = 5 * 5 * 149 is also the 50th pentagonal number. The rest are not figurates, except for 15113 = 7 * 17 * 127, which is the seventeenth 113-figurate number. %Y A144715 Cf. A144325, A144313, A144315, A000326 %K A144715 easy,nonn %O A144715 1,1 %A A144715 _Reikku Kulon_, Sep 19 2008