Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #15 Aug 11 2024 14:41:29
%S 1,99,331,3207,10099,105720053635,10310949321253
%N Numbers n such that n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2 is palindromic.
%C All terms are odd. - _Chai Wah Wu_, Jan 18 2016
%H P. De Geest, <a href="https://www.worldofnumbers.com/sumsquare.htm">Palindromic Sums of Squares of Consecutive Integers</a>
%t Select[Range[15000],PalindromeQ[5(6+4#+#^2)]&] (* The program uses the PalindromeQ function from Mathematica version 10.3 *) (* _Harvey P. Dale_, Nov 02 2015 *)
%o (PARI) isok(n) = my(d = digits(n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2)); d == Vecrev(d); \\ _Michel Marcus_, Jan 24 2016
%Y Cf. A027580.
%K nonn,base,more
%O 1,2
%A _Patrick De Geest_
%E a(6) from _Chai Wah Wu_, Jan 18 2016
%E a(7) from _Giovanni Resta_, Aug 04 2019