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A284635
Numbers with digits 6 and 8 only.
4
6, 8, 66, 68, 86, 88, 666, 668, 686, 688, 866, 868, 886, 888, 6666, 6668, 6686, 6688, 6866, 6868, 6886, 6888, 8666, 8668, 8686, 8688, 8866, 8868, 8886, 8888, 66666, 66668, 66686, 66688, 66866, 66868, 66886, 66888, 68666, 68668, 68686, 68688, 68866, 68868
OFFSET
1,1
COMMENTS
All terms are even.
FORMULA
a(n) = 2 * A032834(n).
MATHEMATICA
Table[FromDigits /@ Tuples[{6, 8}, n], {n, 5}] // Flatten (* or *)
Select[Range@ 70000, Total@ Pick[DigitCount@ #, {0, 0, 0, 0, 0, 1, 0, 1, 0, 0}, 0] == 0 &] (* Michael De Vlieger, Apr 02 2017 *)
PROG
(Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {6, 8}]
(Python)
def a(n): return int(bin(n+1)[3:].replace('0', '6').replace('1', '8'))
print([a(n) for n in range(1, 45)]) # Michael S. Branicky, Jun 08 2021
CROSSREFS
Cf. A032834.
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), A284634 (k = 4), A256291 (k = 5), A256292 (k = 7), this sequence (k = 8), A284636 (k = 9).
Sequence in context: A192383 A322544 A270038 * A250256 A242490 A216796
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Apr 02 2017
STATUS
approved