A045817 Numbers n written in base 7, where in the list of divisors of n (in base 7), each digit 0-6 appears equally often.

3602, 246506, 264533, 266405, 303652, 320556, 324255, 325605, 342560, 345064, 345406, 345604, 346340, 362055, 414056, 430462, 434630, 435065, 436430, 436550, 453605, 500426, 500641, 506022, 524360, 524406, 526433, 530632, 532650, 533402

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

Cf. A038564, A038565, A045818.

Sequence in context: A296907 A157861 A031558 * A107538 A270260 A106433

Adjacent sequences: A045814 A045815 A045816 * A045818 A045819 A045820

Keyword

easy,nonn,base

Author

Naohiro Nomoto

Extensions

Definition clarified by Robert Israel, Sep 07 2018

Status

approved