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 A028386 #18 Apr 15 2025 17:23:36 %S A028386 1,2,4,26,44,101,693,2173,2229,4228,6010,26466,26906,31926,44059, %T A028386 1258723,1965117,1979130,2684561,13280839,59401650,84885761,100058581, %U A028386 225563533,316882086,700457153,818049201,851649306,1345679688,2049123156,6693818696,18306458265,18517422797 %N A028386 Numbers k such that k*(3k-1)/2 is a pentagonal palindrome. %H A028386 Bert Dobbelaere, <a href="/A028386/b028386.txt">Table of n, a(n) for n = 1..57</a> %H A028386 Patrick De Geest, <a href="https://www.worldofnumbers.com/penta.htm">Palindromic Pentagonals</a> %Y A028386 Cf. A002069, A000326. %K A028386 nonn,base %O A028386 1,2 %A A028386 _Patrick De Geest_ %E A028386 More terms from _Patrick De Geest_, Nov 15 1998 %E A028386 More terms from _Bert Dobbelaere_, Apr 15 2025