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A028558 Numbers k such that k*(k+5) is a palindrome.

%I A028558 #29 May 05 2024 08:56:12
%S A028558 0,1,6,18,24,202,203,814,2067,2178,2207,20402,25116,64493,82566,
%T A028558 207067,2040402,2187142,2233097,6887078,79585891,211313148,249281986,
%U A028558 8161664181,22222222222,26331005924,81294635989,2008491060208,2048192235518,2228557243297,2471952825156
%N A028558 Numbers k such that k*(k+5) is a palindrome.
%C A028558 a(34) > 10^13
%H A028558 Lior Manor, <a href="/A028558/b028558.txt">Table of n, a(n) for n = 1..33</a>
%H A028558 Patrick De Geest, <a href="http://www.worldofnumbers.com/consemor.htm">Palindromic Quasipronics of the form n(n+x)</a>
%H A028558 Erich Friedman, <a href="https://erich-friedman.github.io/numbers.html">What's Special About This Number?</a> (See entries 814, 2067.)
%o A028558 (Python)
%o A028558 from itertools import count, islice
%o A028558 def ispal(n): s = str(n); return s == s[::-1]
%o A028558 def agen():
%o A028558     for k in count(0):
%o A028558         if ispal(k*(k+5)):
%o A028558             yield k
%o A028558 print(list(islice(agen(), 20))) # _Michael S. Branicky_, Jan 24 2022
%K A028558 nonn,base
%O A028558 1,3
%A A028558 _Patrick De Geest_
%E A028558 a(21)-a(27) from _Michael S. Branicky_, Jan 24 2022
%E A028558 a(28)-a(31) from _Lior Manor_, May 05 2024