OFFSET
1,1
COMMENTS
a(n) <= n-1 for n >= 12. - Robert Israel, Apr 13 2021
LINKS
Robert Israel, Table of n, a(n) for n = 1..2000
Eric Weisstein's World of Mathematics, Repdigit
EXAMPLE
n=11: 121=11*11 in binary = '1111001', but in ternary = '11111', therefore a(11)=3;
n=93: 1023=11*93 in binary = '1111111111', therefore a(93)=2.
MAPLE
f:= proc(n) local b, d, m;
for b from 2 do
d:= (11*n) mod b;
m:= ceil(log[b](11*n));
if 11*n = d*(b^m-1)/(b-1) then return b fi
od
end proc:
map(f, [$1..100]); # Robert Israel, Apr 13 2021
CROSSREFS
KEYWORD
AUTHOR
Reinhard Zumkeller, Mar 10 2004
STATUS
approved