A284634 - OEIS

%I #12 Sep 08 2022 08:46:19

%S 4,6,44,46,64,66,444,446,464,466,644,646,664,666,4444,4446,4464,4466,

%T 4644,4646,4664,4666,6444,6446,6464,6466,6644,6646,6664,6666,44444,

%U 44446,44464,44466,44644,44646,44664,44666,46444,46446,46464,46466,46644,46646

%N Numbers with digits 4 and 6 only.

%C All terms are even.

%F a(n) = 2 * A032810(n).

%t Table[FromDigits /@ Tuples[{4, 6}, n], {n, 5}] // Flatten (* or *)

%t Select[Range@ 50000, Total@ Pick[DigitCount@ #, {0, 0, 0, 1, 0, 1, 0, 0, 0, 0}, 0] == 0 &] (* _Michael De Vlieger_, Apr 02 2017 *)

%o (Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {4, 6}]

%Y Numbers n with digits 6 and k only for k = 0 - 5 and 7 - 9: A204093 (k = 0), A284293 (k = 1), A284632 (k = 2), A284633 (k = 3), this sequence (k = 4), A256291 (k = 5), A256292 (k = 7), A284635 (k = 8), A284636 (k = 9).

%K nonn,base

%O 1,1

%A _Jaroslav Krizek_, Apr 02 2017