OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Multiplicative Digital Root
MAPLE
A031347:= proc(n) local x;
x:= n;
while x > 10 do
x:= convert(convert(x, base, 10), `*`)
od;
x
end proc:
select(A031347=8, [$1..1000]); # Robert Israel, Aug 10 2026
MATHEMATICA
dr8Q[n_]:=NestWhile[Times@@IntegerDigits[#]&, n, #>9&]==8; Select[ Range[ 250], dr8Q] (* Harvey P. Dale, Jun 10 2011 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Patrick De Geest, Sep 15 1998
STATUS
approved