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A043356 Numbers having four 1's in base 5.

%I A043356 #21 Apr 28 2025 14:58:40
%S A043356 156,656,756,776,780,782,783,784,786,791,796,806,831,856,906,1031,
%T A043356 1156,1406,2031,2656,3156,3256,3276,3280,3282,3283,3284,3286,3291,
%U A043356 3296,3306,3331,3356,3406,3531,3656,3756,3776,3780
%N A043356 Numbers having four 1's in base 5.
%H A043356 Robert Israel, <a href="/A043356/b043356.txt">Table of n, a(n) for n = 1..10000</a>
%p A043356 F:= proc(d,m) option remember;
%p A043356   local A,B;
%p A043356   if m > d then return [] fi;
%p A043356   if d = 0 then return [0] fi;
%p A043356   A:= seq(seq(seq(t+i*5^(d-1),t=procname(dd,m)),dd = 0..d-1),i=2..4);
%p A043356   if m = 0 then [A]
%p A043356   else [seq(seq(t+5^(d-1),t=procname(dd,m-1)),dd=0..d-1),A]
%p A043356   fi
%p A043356 end proc:
%p A043356 map(op,[seq(F(d,4),d=4..6)]); # _Robert Israel_, Jul 02 2018
%t A043356 Select[Range[4000],DigitCount[#,5,1]==4&] (* _Harvey P. Dale_, Apr 28 2025 *)
%o A043356 (PARI) isok(n) = #select(x->(x==1), digits(n, 5)) == 4; \\ _Michel Marcus_, Jul 02 2018
%Y A043356 Cf. A007091 (numbers in base 5).
%K A043356 nonn,base
%O A043356 1,1
%A A043356 _Clark Kimberling_