A043452 Numbers having four 7's in base 8.

4095, 8191, 12287, 16383, 20479, 24575, 28671, 29183, 29695, 30207, 30719, 31231, 31743, 32255, 32319, 32383, 32447, 32511, 32575, 32639, 32703, 32711, 32719, 32727, 32735, 32743, 32751, 32759, 32760, 32761, 32762, 32763, 32764, 32765, 32766, 36863, 40959, 45055

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

G:= proc(x, c, d) local L, m1, m2;
     L:= convert(x, base, 7);
     m2:= nops(c);
     m1:= min(nops(L), m2);
     8^d-1 + add((L[i]-7)*8^(c[i]-1), i=1..m1) - 7*add(8^(c[i]-1), i = m1+1..m2)
end proc:
sort([seq(seq(G(x, c, 6), x = 0 .. 7^2-1), c=combinat:-choose(6, 2))]); # Robert Israel, Sep 24 2017

Mathematica

Select[Range[0, 10^5], DigitCount[#, 8, 7]==4 &] (* Vincenzo Librandi, Sep 25 2017 *)

Prog

(PARI) isok(n) = #select(x->(x==7), digits(n, 8)) == 4; \\ Michel Marcus, Sep 25 2017

Crossrefs

Cf. A007094.

Sequence in context: A103289 A038463 A359084 * A261593 A290869 A075952

Adjacent sequences: A043449 A043450 A043451 * A043453 A043454 A043455

Keyword

nonn,base

Author

Clark Kimberling

Status

approved