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A062130
A062128 written in base 10.
7
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
0,3
EXAMPLE
23 -> 23 + 29 = 52 -> 52 + 11 = 63, so a(23) = 63.
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 *)
PROG
(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; .
CROSSREFS
KEYWORD
base,easy,sign
AUTHOR
Klaus Brockhaus, Jun 06 2001
STATUS
approved