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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.
2
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, 93, 0, 31, 0, 33, 0, 99, 0, 165, 0, 231, 0, 297, 0, 107, 0, 45, 0, 495, 0, 561, 0, 51, 0, 693, 0, 119, 0, 313, 0, 443, 0, 189, 0, 63, 0, 65, 0, 195, 0, 325, 0, 455, 0
OFFSET
1,3
COMMENTS
Base-2 analog of A347346.
FORMULA
If n is odd, then a(n) = A161501(A030101(i)).
PROG
(Python)
def A347347(n):
if n % 2 == 0:
return 0
s = bin(n)[2:]
if s == s[::-1]:
return n
for i in range(1, len(s)):
if s[:-i]== s[-i-1::-1]:
return int(s[:-i-1:-1]+s, 2)
CROSSREFS
KEYWORD
nonn,base,look
AUTHOR
Chai Wah Wu, Aug 27 2021
STATUS
approved