OFFSET
1,2
COMMENTS
The repunit numbers > 0 (A002275) are in the sequence.
From Robert Israel, May 28 2014: (Start)
The possibilities for the digits are as follows:
only 1's: any number of digits;
only 5's or only 6's: any number of digits >= 2;
only 4's or only 9's: any even number of digits;
only 2's, only 3's, only 7's or only 8's: any number of digits == 2 mod 4;
even number of 4's and any number of 6's;
even number of 9's and any number of 1's;
m 2's and n 8's, or m 3's and n 7's, where m - n == 2 mod 4. (End)
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
464 is in the sequence because the digits 4,6,4 satisfy
4 = (6*4) mod 10;
6 = (4*4) mod 10;
4 = (4*6) mod 10.
MAPLE
filter:= proc(n) local L;
L:= convert(n, base, 10);
if not member(convert(L, set), {{1}, {2}, {3}, {4}, {5}, {6}, {7}, {8}, {9}, {1, 9}, {2, 8}, {3, 7}, {4, 6}}) then return false fi;
andmap(t -> convert(subsop(t=1, L), `*`) mod 10 = L[t], [$1..nops(L)]);
end proc;
select(filter, [$1..10^5]); # Robert Israel, May 28 2014
MATHEMATICA
Select[Range[10^4], IntegerDigits[#] == Mod[Times@@IntegerDigits[#]/IntegerDigits[#], 10]&]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Jun 08 2013
EXTENSIONS
Edited by Jon E. Schoenfield, Sep 09 2017
STATUS
approved