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 A027571 #32 Jun 01 2021 03:12:45 %S A027571 0,1,9,12,16,919,1257,1262,1621,1706,170706,904280,1258182,7901014, %T A027571 8659929,12458597,17070706,80472264,1616689803,1680689788,1705387643, %U A027571 7360311900,8032814139,8055329360,12574461617,16794058711,165058650666,844706005220,1250999800012,1255589965852 %N A027571 Numbers k such that k^2 + (k+1)^2 is palindromic. %C A027571 a(50) > 70710678118654752440. - _Patrick De Geest_, May 25 2021 %H A027571 Patrick De Geest, <a href="/A027571/b027571.txt">Table of n, a(n) for n = 1..49</a> (terms a(1)..a(29) from Giovanni Resta) %H A027571 Patrick De Geest, <a href="http://www.worldofnumbers.com/sumsquare.htm">Palindromic Sums of Squares of Consecutive Integers</a> %H A027571 Patrick De Geest, <a href="http://www.worldofnumbers.com/centered.htm">Palindromic Centered Polygonal Numbers</a> %o A027571 (PARI) isok(m) = my(d=digits(m^2+(m+1)^2)); d == Vecrev(d); \\ _Michel Marcus_, Jan 05 2019 %Y A027571 Cf. A001844, A027572, A050236, A050239. %Y A027571 A050236 is a subsequence. %K A027571 nonn,base %O A027571 1,3 %A A027571 _Patrick De Geest_ %E A027571 a(18)-a(21) from _Donovan Johnson_, Aug 26 2012 %E A027571 a(22)-a(29) from _Giovanni Resta_, Aug 06 2019 %E A027571 a(1)=0 added by _Patrick De Geest_, May 25 2021