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 A050785 #18 Jan 20 2025 12:57:30 %S A050785 11,22,33,44,55,66,77,88,99,111,222,333,444,555,666,777,888,999,1001, %T A050785 1111,1221,1331,1441,1551,1661,1771,1881,1991,2002,2112,2222,2332, %U A050785 2442,2552,2662,2772,2882,2992,3003,3113,3223,3333,3443,3553,3663,3773,3883,3993,4004,4114,4224,4334,4444 %N A050785 Palindromes containing at least one pair of consecutive equal digits. %H A050785 J.W.L. (Jan) Eerland, <a href="/A050785/b050785.txt">Table of n, a(n) for n = 1..43569</a> %t A050785 Select[Range[3900],Reverse[x=IntegerDigits[#]]==x&&MemberQ[Differences[x],0]&] (* _Jayanta Basu_, Jun 01 2013 *) %Y A050785 Cf. A002113, A050786, A050783. %K A050785 nonn,easy,base %O A050785 1,1 %A A050785 _Patrick De Geest_, Sep 15 1999 %E A050785 a(48)-a(53) from _J.W.L. (Jan) Eerland_, Jan 20 2025