|
%I #22 Feb 21 2024 16:55:43
%S 2,22,202,212,222,232,242,252,262,272,282,292,2002,2112,2222,2332,
%T 2442,2552,2662,2772,2882,2992,20002,20102,20202,20302,20402,20502,
%U 20602,20702,20802,20902,21012,21112,21212,21312,21412,21512,21612,21712,21812,21912
%N Base-10 palindromes that start with 2.
%H Jaroslav Krizek, <a href="/A043037/b043037.txt">Table of n, a(n) for n = 1..2222</a>
%t palQ[n_Integer, base_Integer] := Module[{idn = IntegerDigits[n, base]}, idn == Reverse[idn]]; Select[Range[0, 100000], IntegerDigits[#][[1]] == 2 && palQ[#, 10] &] (* _T. D. Noe_, Mar 12 2013 *)
%t Select[Range[22000],PalindromeQ[#]&&IntegerDigits[#][[1]]==2&] (* _Harvey P. Dale_, Feb 21 2024 *)
%o (PARI) isok(n) = (d=digits(n)) && (d[1]==2) && (Vecrev(d)==d); \\ _Michel Marcus_, Aug 22 2015
%Y Cf. A002113.
%K nonn,base
%O 1,1
%A _Clark Kimberling_
|
