A062130 A062128 written in base 10.

0, 1, 3, 3, 5, 5, 9, 7, 9, 9, 15, 27, 15, 27, 21, 15, 17, 17, 27, 99, 99, 21, -1, 63, 27, 99, -1, 27, -1, 63, 45, 31, 33, 33, 51, -1, 45, -1, 63, 99, 45, -1, 63, 99, 99, 45, -1, -1, 51, -1, 255, 51, 63, 99, 255, 153, 63, 99, 255, 153, -1, -1, 93, 63, 65, 65, 99, -1, 85, 255, 119, 387, 255, 73, 13299, -1, 387, -1, -1, 219, 85

Offset: 0

Author

Klaus Brockhaus, Jun 06 2001

Keywords

• base
• easy
• sign

Examples

			23 -> 23 + 29 = 52 -> 52 + 11 = 63, so a(23) = 63.
		

Links

• Index entries for sequences related to Reverse and Add!
• Klaus Brockhaus, On the'Reverse and Add!' algorithm in base 2

Crossrefs

Cf. A033865, A062128, A062131, A061561.

Programs

ARIBAS

stop := 500; for k := 0 to 80 do c := 0; m := k; rev := bit_reverse(m); while m <> rev and c < stop do inc(c); m := m + rev; rev := bit_reverse(m); end; if c < stop then write(m); else write(-1); end; write(" "); end;.

Mathematica

limit = 10^4; (* Assumes that there is no palindrome if none is found before "limit" iterations *)
Table[np = n; i = 0;
 While[np != IntegerReverse[np, 2] && i < limit,
  np = np + IntegerReverse[np, 2]; i++];
If[i >= limit, -1, np], {n, 0, 80}] (* Robert Price, Oct 14 2019 *)