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A284634
Numbers with digits 4 and 6 only.
7
4, 6, 44, 46, 64, 66, 444, 446, 464, 466, 644, 646, 664, 666, 4444, 4446, 4464, 4466, 4644, 4646, 4664, 4666, 6444, 6446, 6464, 6466, 6644, 6646, 6664, 6666, 44444, 44446, 44464, 44466, 44644, 44646, 44664, 44666, 46444, 46446, 46464, 46466, 46644, 46646
OFFSET
1,1
COMMENTS
All terms are even.
FORMULA
a(n) = 2 * A032810(n).
MATHEMATICA
Table[FromDigits /@ Tuples[{4, 6}, n], {n, 5}] // Flatten (* or *)
Select[Range@ 50000, Total@ Pick[DigitCount@ #, {0, 0, 0, 1, 0, 1, 0, 0, 0, 0}, 0] == 0 &] (* Michael De Vlieger, Apr 02 2017 *)
PROG
(Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {4, 6}]
CROSSREFS
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).
Sequence in context: A013022 A012908 A306842 * A370619 A077100 A012935
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Apr 02 2017
STATUS
approved