A043356 Numbers having four 1's in base 5.

156, 656, 756, 776, 780, 782, 783, 784, 786, 791, 796, 806, 831, 856, 906, 1031, 1156, 1406, 2031, 2656, 3156, 3256, 3276, 3280, 3282, 3283, 3284, 3286, 3291, 3296, 3306, 3331, 3356, 3406, 3531, 3656, 3756, 3776, 3780

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A007091 (numbers in base 5).

Programs

Maple

F:= proc(d,m) option remember;
  local A,B;
  if m > d then return [] fi;
  if d = 0 then return [0] fi;
  A:= seq(seq(seq(t+i*5^(d-1),t=procname(dd,m)),dd = 0..d-1),i=2..4);
  if m = 0 then [A]
  else [seq(seq(t+5^(d-1),t=procname(dd,m-1)),dd=0..d-1),A]
  fi
end proc:
map(op,[seq(F(d,4),d=4..6)]); # Robert Israel, Jul 02 2018

Mathematica

Select[Range[4000],DigitCount[#,5,1]==4&] (* Harvey P. Dale, Apr 28 2025 *)

PARI

isok(n) = #select(x->(x==1), digits(n, 5)) == 4; \\ Michel Marcus, Jul 02 2018