

A308365


Numbers which are products of repunits.


4



1, 11, 111, 121, 1111, 1221, 1331, 11111, 12221, 12321, 13431, 14641, 111111, 122221, 123321, 134431, 135531, 147741, 161051, 1111111, 1222221, 1233321, 1234321, 1344431, 1356531, 1367631, 1478741, 1490841, 1625151, 1771561, 11111111, 12222221, 12333321
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OFFSET

1,2


COMMENTS

The number of terms below 10^n is A216053(n)1 for 1 <= n <= 25, but not for larger n.  Rémy Sigrist, May 28 2019


LINKS



EXAMPLE

a(11) = 13431 is in the sequence since it is the product of repunits (11^2*111).


MAPLE

d:= 10: # for terms < 10^d
N:= 10^d:
S:= {1}:
for m from 2 to d do
r:= (10^m1)/9;
k:= floor(log[r](N));
V:= S;
for i from 1 to k do
V:= select(`<`, map(`*`, V, r), N);
S:= S union V
od;
od:


CROSSREFS



KEYWORD

nonn,base


AUTHOR



EXTENSIONS



STATUS

approved



