This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A175240 Call any positive integer that is a palindrome when written in binary a "binary palindrome". a(n) = the smallest binary palindrome such that a(n)*(the n-th binary palindrome) is not a binary palindrome. 1
 27, 5, 5, 9, 5, 17, 5, 3, 5, 33, 3, 7, 5, 65, 9, 5, 3, 15, 3, 3, 5, 129, 3, 5, 3, 27, 3, 5, 5, 257, 17, 5, 3, 5, 5, 3, 3, 27, 3, 3, 3, 5, 3, 3, 5, 513, 3, 9, 3, 5, 3, 3, 3, 27, 7, 3, 3, 5, 3, 5, 5, 1025, 33, 5, 3, 9, 5, 3, 3, 5, 5, 5, 3, 3, 3, 3, 3, 27, 3, 3, 5, 3, 3, 3, 3, 5, 3, 3, 3, 5, 3, 3, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS There are no palindromes that work for a(1), since the first positive binary palindrome is 1. (The n-th positive binary palindrome)*a(n) = A175241(n), a non-palindrome when written in binary. LINKS EXAMPLE The 6th positive integer that is a palindrome when written in binary is 15, which is 1111 in binary. Checking the binary palindromes multiplied by 15: 1*15 = 15, which is 1111 in binary, a palindrome. 3, 11 in binary, is the second positive binary palindrome. 3*15 = 45, which is 101101 in binary, a palindrome. 5, 101 in binary, is the 3rd positive binary palindrome. 5*15 = 75, which is 1001011 in binary, not a palindrome. Since 5*15 is not a palindrome in binary, then a(6) (the 5th term of the sequence) is 5. CROSSREFS Cf. A006995, A175241. Sequence in context: A040712 A040714 A040711 * A204877 A040709 A218014 Adjacent sequences:  A175237 A175238 A175239 * A175241 A175242 A175243 KEYWORD base,nonn AUTHOR Leroy Quet, Mar 11 2010 EXTENSIONS Extended by Ray Chandler, Mar 13 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 18 12:18 EDT 2019. Contains 328160 sequences. (Running on oeis4.)