OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..161
N. Nomoto, In the list of divisors of n,... [broken link]
EXAMPLE
E.g., divisors of 342560 (base 7) are (1,2,10,20,15463,34256,154630,342560) (all in base 7); the numbers of digits (0-6) are [0(4),1(4),2(4),3(4),4(4),5(4),6(4)].
MAPLE
N:= 7^6:
cv7:= proc(n) local L; L:= convert(n, base, 7);
add(L[i]*10^(i-1), i=1..nops(L)) end proc:
V:= Matrix(N, 7, datatype=integer[8]):
count:= 0: Res:= NULL:
for i from 1 to N do
L:= convert(i, base, 7);
M:= Vector[row]([seq(numboccur(d, L), d=0..6)], datatype=integer[8]);
for r from i to N by i do V[r, ..]:= V[r, ..] + M od;
if nops(convert(V[i, ..], set))=1 then
count:= count+1;
w:= cv7(i);
Res:= Res, w;
fi
od:
Res; # Robert Israel, Sep 07 2018
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
EXTENSIONS
Definition clarified by Robert Israel, Sep 07 2018
STATUS
approved