cp's OEIS Frontend

A347347 If n is odd, a(n) is the smallest positive integer that is a palindrome when represented in binary, and is made by appending some number (zero or more) of binary digits on the left of n's binary representation. If n is even, then a(n) = 0.

%I A347347 #16 Aug 30 2021 17:19:17
%S A347347 1,0,3,0,5,0,7,0,9,0,27,0,45,0,15,0,17,0,51,0,21,0,119,0,153,0,27,0,
%T A347347 93,0,31,0,33,0,99,0,165,0,231,0,297,0,107,0,45,0,495,0,561,0,51,0,
%U A347347 693,0,119,0,313,0,443,0,189,0,63,0,65,0,195,0,325,0,455,0
%N A347347 If n is odd, a(n) is the smallest positive integer that is a palindrome when represented in binary, and is made by appending some number (zero or more) of binary digits on the left of n's binary representation. If n is even, then a(n) = 0.
%C A347347 Base-2 analog of A347346.
%H A347347 Chai Wah Wu, <a href="/A347347/b347347.txt">Table of n, a(n) for n = 1..10000</a>
%F A347347 If n is odd, then a(n) = A161501(A030101(i)).
%o A347347 (Python)
%o A347347 def A347347(n):
%o A347347     if n % 2 == 0:
%o A347347         return 0
%o A347347     s = bin(n)[2:]
%o A347347     if s == s[::-1]:
%o A347347         return n
%o A347347     for i in range(1,len(s)):
%o A347347         if s[:-i]== s[-i-1::-1]:
%o A347347             return int(s[:-i-1:-1]+s,2)
%Y A347347 Cf. A030101, A161501, A347346.
%K A347347 nonn,base,look
%O A347347 1,3
%A A347347 _Chai Wah Wu_, Aug 27 2021