OFFSET
0,1
COMMENTS
Take a number n, create a table with d columns and rows where d=number of digits of n. Each column corresponds to a digit of n and each row to a digit of n. In each cell, multiply the two digits of n represented by that row and column. Add up the sums of all of the rows and all of the columns to get a new number m which divides n.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
EXAMPLE
512 / (2*(5*5 + 5*1 + 5*2 + 1*5 + 1*1 + 1*2 + 2*5 + 2*1 + 2*2)) = 4.
MATHEMATICA
Select[Range[15000], !Divisible[#, 10]&&Divisible[#, 2Total[Times @@@ Tuples[ IntegerDigits[#], 2]]]&] (* Harvey P. Dale, Aug 19 2014 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Chuck Seggelin (barkeep(AT)plastereddragon.com), Jun 30 2003
STATUS
approved