OFFSET
0,2
COMMENTS
a(n) = -1 if and only if m ends with the digit 5.
LINKS
EXAMPLE
For n = 30 we have m = 3; 3*2 = 6 is a palindrome with even digits, so a(30) = 2.
PROG
(ARIBAS): stop := 500000; for n := 0 to 80 do k := 1; test := true; while test and k < stop do mp := omit_trailzeros(n)*k; if test := not all_even(mp) or mp <> int_reverse(mp) then inc(k); end; end; if k < stop then write(k, " "); else write(-1, " "); end; end;
CROSSREFS
KEYWORD
base,easy,sign
AUTHOR
Klaus Brockhaus, Jun 25 2001
STATUS
approved