A061917 - OEIS

A061917

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

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, 90, 99, 100, 101, 110, 111, 121, 131, 141, 151, 161, 171, 181, 191, 200, 202, 212, 220, 222, 232, 242, 252, 262, 272, 282, 292, 300, 303, 313, 323, 330, 333, 343, 353, 363, 373, 383, 393, 400, 404

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Numbers that are palindromes when written with a suitable number of leading zeros. - Jeppe Stig Nielsen, Jan 17 2022

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

A136522(A004151(a(n))) = 1. - Reinhard Zumkeller, Sep 25 2011

MATHEMATICA

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 *)

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

PROG

(Haskell)

a061917 n = a061917_list !! (n-1)

a061917_list = filter chi [0..] where

chi x = zs == reverse zs where

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

-- Reinhard Zumkeller, Sep 25 2011

(PARI) isOK(k)=k==0||fromdigits(Vecrev(digits(k)))==k/10^valuation(k, 10) \\ Jeppe Stig Nielsen, Jan 17 2022

(Python)

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

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

print([k for k in range(405) if ok(k)]) # Michael S. Branicky, Jan 17 2022