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A028561 Numbers k such that k*(k+6) is a palindrome.

%I A028561 #24 Jan 26 2022 09:05:31
%S A028561 0,1,5,22,137,273,715,863,2731,8541,486618,877173,1378507,1731746,
%T A028561 2273915,2436099,5401396,7153679,7560069,14529486,23887419,23975475,
%U A028561 73114035,84890503,88837611,235680755,235769755,272515513,440021417,782357262,1414071397,2352019439
%N A028561 Numbers k such that k*(k+6) is a palindrome.
%H A028561 Michael S. Branicky, <a href="/A028561/b028561.txt">Table of n, a(n) for n = 1..35</a>
%H A028561 Patrick De Geest, <a href="http://www.worldofnumbers.com/consemor.htm">Palindromic Quasipronics of the form n(n+x)</a>
%H A028561 Erich Friedman, <a href="https://erich-friedman.github.io/numbers.html">What's Special About This Number?</a> (See entries 863, 8541.)
%t A028561 Select[Range[0,24*10^6],PalindromeQ[#(#+6)]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 04 2017 *)
%o A028561 (Python)
%o A028561 from itertools import count, islice
%o A028561 def ispal(n): s = str(n); return s == s[::-1]
%o A028561 def agen():
%o A028561     for k in count(0):
%o A028561         if ispal(k*(k+6)):
%o A028561             yield k
%o A028561 print(list(islice(agen(), 22))) # _Michael S. Branicky_, Jan 25 2022
%Y A028561 Cf. A002113, A028560, A028562.
%K A028561 nonn,base
%O A028561 1,3
%A A028561 _Patrick De Geest_
%E A028561 a(23) and beyond from _Michael S. Branicky_, Jan 25 2022