A061917 - OEIS

%I #29 Jan 18 2022 03:31:48

%S 0,1,2,3,4,5,6,7,8,9,10,11,20,22,30,33,40,44,50,55,60,66,70,77,80,88,

%T 90,99,100,101,110,111,121,131,141,151,161,171,181,191,200,202,212,

%U 220,222,232,242,252,262,272,282,292,300,303,313,323,330,333,343,353,363,373,383,393,400,404

%N Either a palindrome or becomes a palindrome if trailing 0's are omitted.

%C Numbers that are palindromes when written with a suitable number of leading zeros. - _Jeppe Stig Nielsen_, Jan 17 2022

%H Reinhard Zumkeller, <a href="/A061917/b061917.txt">Table of n, a(n) for n = 1..10000</a>

%F A136522(A004151(a(n))) = 1. - _Reinhard Zumkeller_, Sep 25 2011

%t PaleQ[n_Integer, base_Integer] := Module[{idn, trim = n/base^IntegerExponent[n, base]}, idn = IntegerDigits[trim, base]; idn == Reverse[idn]]; Select[Range[0, 500], PaleQ[#, 10] &] (* _Lei Zhou_, Dec 13 2013 *)

%t Join[{0},Select[Range[500],PalindromeQ[FromDigits[Drop[IntegerDigits[#],-IntegerExponent[#,10]]]]&]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 27 2017 *)

%o (Haskell)

%o a061917 n = a061917_list !! (n-1)

%o a061917_list = filter chi [0..] where

%o    chi x = zs == reverse zs where

%o       zs = dropWhile (== '0') $ reverse $ show x

%o -- _Reinhard Zumkeller_, Sep 25 2011

%o (PARI) isOK(k)=k==0||fromdigits(Vecrev(digits(k)))==k/10^valuation(k,10) \\ _Jeppe Stig Nielsen_, Jan 17 2022

%o (Python)

%o def ispal(s): return s == s[::-1]

%o def ok(n): s = str(n); return ispal(s) or ispal(s.rstrip('0'))

%o print([k for k in range(405) if ok(k)]) # _Michael S. Branicky_, Jan 17 2022

%Y Cf. A002113, A057890, A057891.

%K nonn,base,easy,nice

%O 1,3

%A _N. J. A. Sloane_, Jun 27 2001

%E Corrected by _Ray Chandler_, Jun 08 2009