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 A027580 #29 Aug 11 2024 14:41:29
%S A027580 55,51015,554455,51488415,510151015,55883648705050784638855,
%T A027580 531578379527444725973875135
%N A027580 Palindromes of the form n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2.
%C A027580 Terms start and end with the digit 5 since all terms are divisible by 5, i.e., the corresponding values of n are odd (see A027579). - _Chai Wah Wu_, Jan 18 2016
%H A027580 P. De Geest, <a href="https://www.worldofnumbers.com/sumsquare.htm">Palindromic Sums of Squares of Consecutive Integers</a>
%t A027580 Select[Table[n^2 + (n + 1)^2 + (n + 2)^2 + (n + 3)^2 + (n + 4)^2, {n, 10^7}], # == Reverse@ # &@ IntegerDigits@ # &] (* _Michael De Vlieger_, Jan 24 2016 *)
%t A027580 Select[Table[5x^2+20x+30,{x,11000}],PalindromeQ] (* The program generates the first 5 terms of the sequence. To generate more, increase the x constant but the program may take a long time to run. *) (* _Harvey P. Dale_, Sep 16 2023 *)
%o A027580 (Python)
%o A027580 A027580_list = []
%o A027580 for i in range(1,10**8,2):
%o A027580 s = str(5*(i*(i+4)+6))
%o A027580 if s == s[::-1]:
%o A027580 A027580_list.append(int(s)) # _Chai Wah Wu_, Jan 18 2016
%Y A027580 Cf. A027579.
%K A027580 nonn,base,more
%O A027580 1,1
%A A027580 _Patrick De Geest_
%E A027580 a(6) from _Chai Wah Wu_, Jan 18 2016
%E A027580 a(7) from _Giovanni Resta_, Aug 04 2019