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 A195903 #42 Jun 05 2025 13:54:56 %S A195903 1,2,101,174,211,249,257,1822,2070,20795,9531980,17880587,215198695, %T A195903 1702002467,167526192487,196759830168,2036493584526,17476134422427, %U A195903 82406037714600,170438376135142,181002188703854,189344689666188,213031868452710,10020895012660701,17108271682888342 %N A195903 Numbers m such that m-th centered triangular number is a palindrome. %C A195903 Computed by _Robert G. Wilson v_. %C A195903 a(18) > 2581988897472. - _Donovan Johnson_, Sep 29 2011 %C A195903 a(31) > 81649658092772603272. - _Patrick De Geest_, May 23 2021 %H A195903 Patrick De Geest, <a href="/A195903/b195903.txt">Table of n, a(n) for n = 1..30</a> %H A195903 Terry Trotter, <a href="http://trottermath.net/polygonal-numbers/">Polygonal numbers</a> [numbers >=920 on this page were incorrect when accessed Sep 25 2011] %H A195903 Terry Trotter, <a href="https://web.archive.org/web/20160420101547/http://trottermath.net/polygonal-numbers/">Polygonal Numbers</a>, from the Wayback machine %H A195903 Patrick De Geest, <a href="http://www.worldofnumbers.com/centered.htm">Palindromic Centered Polygonal Numbers</a> %Y A195903 Cf. A005448, A162703. %K A195903 nonn,base %O A195903 1,2 %A A195903 _Kausthub Gudipati_, Sep 25 2011 %E A195903 a(14) from _D. S. McNeil_, Sep 26 2011 %E A195903 a(15)-a(17) from _Donovan Johnson_, Sep 29 2011 %E A195903 a(18)-a(30) from _Patrick De Geest_, May 23 2021