OFFSET
1,3
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..81
Patrick De Geest, Palindromic numbers beyond base 10
MAPLE
N:= 9: # to get all terms with up to N decimal digits
qpali:= proc(k, b) local L; L:= convert(k, base, b); if L = ListTools:-Reverse(L) then k else NULL fi end proc:
digrev:= proc(k, b) local L, n; L:= convert(k, base, b); n:= nops(L); add(L[i]*b^(n-i), i=1..n); end proc:
Res:= $0..9:
for d from 2 to N do
if d::even then
m:= d/2;
Res:= Res, seq(qpali(n*10^m + digrev(n, 10), 16), n=10^(m-1)..10^m-1);
else
m:= (d-1)/2;
Res:= Res, seq(seq(qpali(n*10^(m+1)+y*10^m+digrev(n, 10), 16), y=0..9), n=10^(m-1)..10^m-1);
fi
od:
Res; # Robert Israel, Nov 23 2014
MATHEMATICA
A029731Q = PalindromeQ@# && IntegerReverse[#, 16] == # &; Select[Range[10^5], A029731Q] (* JungHwan Min, Mar 02 2017 *)
Select[Range[10^7], Times @@ Boole@ Map[# == Reverse@ # &, {IntegerDigits@ #, IntegerDigits[#, 16]}] > 0 &] (* Michael De Vlieger, Mar 03 2017 *)
PROG
(Python)
def palQ16(n): # check if n is a palindrome in base 16
s = hex(n)[2:]
return s == s[::-1]
def palQgen10(l): # unordered generator of palindromes of length <= 2*l
if l > 0:
yield 0
for x in range(1, 10**l):
s = str(x)
yield int(s+s[-2::-1])
yield int(s+s[::-1])
A029731_list = sorted([n for n in palQgen10(6) if palQ16(n)])
# Chai Wah Wu, Nov 25 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved