A062129 In base 2: start with n; add to itself with digits reversed; if palindrome, stop; otherwise repeat; a(n) gives palindrome at which it stops, or -1 if no palindrome is ever reached.

0, 11, 11, 1001, 101, 1111, 1001, 10101, 1001, 11011, 1111, 11011, 1111, 11011, 10101, 101101, 10001, 110011, 11011, 1100011, 1100011, 111111, -1, 111111, 11011, 1100011, -1, 11111111, -1, 111111, 101101, 1011101, 100001, 1100011, 110011, -1, 101101, -1, 111111, 1100011, 101101, -1, 111111

Offset: 0

Author

Klaus Brockhaus, Jun 06 2001

Keywords

• base
• easy
• sign

Comments

The analog of A061563 in base 2. Differs from A062128 only for those n, which are palindromes in base 2.

Examples

			23: 10111 -> 10111 + 11101 = 110100 -> 110100 + 1011 = 111111, so a(23) = 111111.
		

Crossrefs

Cf. A061563, A062128, A062131, A058042.

Programs

ARIBAS

stop := 500; for k := 0 to 60 do c := 0; m := k; test := true; while test and c < stop do inc(c); m := m + bit_reverse(m); test := m <> bit_reverse(m); end; if c < stop then bit_write(m); else write(-1); end; write(" "); end;