A045240 - OEIS

%I #17 Dec 11 2023 08:39:03

%S 6,26,30,32,34,36,46,56,106,126,130,132,134,136,146,150,152,154,160,

%T 162,164,170,172,174,176,180,182,184,186,196,226,230,232,234,236,246,

%U 256,276,280,282,284,286,296,306,356,506,526,530

%N Numbers whose base-5 representation contains exactly two 1's and no 3's.

%H Robert Israel, <a href="/A045240/b045240.txt">Table of n, a(n) for n = 1..10000</a>

%p A0[1]:= {2,4}:

%p A1[1]:= {1}:

%p A11[1]:= {}:

%p count:= 0:

%p for n from 2 while count < 1000 do

%p   A0[n]:= map(t -> (5*t, 5*t+2, 5*t+4), A0[n-1]);

%p   A1[n]:= map(t -> (5*t,5*t+2,5*t+4), A1[n-1]) union map(t -> 5*t+1, A0[n-1]);

%p   A11[n]:= map(t -> (5*t,5*t+2,5*t+4), A11[n-1]) union map(t -> 5*t+1, A1[n-1]);

%p   count:= count + nops(A11[n]);

%p od:

%p sort([seq(op(A11[i]),i=1..n-1)]); # _Robert Israel_, Dec 10 2023

%Y Cf. A007091.

%K nonn,base

%O 1,1

%A _Clark Kimberling_