cp's OEIS Frontend

A028564 Numbers k such that k*(k+7) is a palindrome.

%I A028564 #18 Jan 26 2022 18:20:16
%S A028564 0,1,4,19,26,219,664,902,2109,2972,2982,9002,21009,29696,90002,210009,
%T A028564 223114,292967,669024,900002,942997,2100009,2109664,2219779,8972876,
%U A028564 9000002,21000009,21037924,21117304,21152824,21155344,28867722,29802897,29857886,90000002
%N A028564 Numbers k such that k*(k+7) is a palindrome.
%H A028564 Michael S. Branicky, <a href="/A028564/b028564.txt">Table of n, a(n) for n = 1..49</a>
%H A028564 Patrick De Geest, <a href="http://www.worldofnumbers.com/consemor.htm">Palindromic Quasipronics of the form n(n+x)</a>
%H A028564 Erich Friedman, <a href="https://erich-friedman.github.io/numbers.html">What's Special About This Number?</a> (See entries 664, 902, 2109, 2982, 9002.)
%o A028564 (Python)
%o A028564 from itertools import count, islice
%o A028564 def ispal(n): s = str(n); return s == s[::-1]
%o A028564 def agen():
%o A028564     for k in count(0):
%o A028564         if ispal(k*(k+7)):
%o A028564             yield k
%o A028564 print(list(islice(agen(), 26))) # _Michael S. Branicky_, Jan 26 2022
%Y A028564 Cf. A028563, A028565.
%K A028564 nonn,base
%O A028564 1,3
%A A028564 _Patrick De Geest_
%E A028564 a(32) and beyond from _Michael S. Branicky_, Jan 26 2022