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A284381
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Numbers n with digits 5 and 8 only.
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4
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5, 8, 55, 58, 85, 88, 555, 558, 585, 588, 855, 858, 885, 888, 5555, 5558, 5585, 5588, 5855, 5858, 5885, 5888, 8555, 8558, 8585, 8588, 8855, 8858, 8885, 8888, 55555, 55558, 55585, 55588, 55855, 55858, 55885, 55888, 58555, 58558, 58585, 58588, 58855, 58858
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OFFSET
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1,1
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COMMENTS
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All terms except the first are composite.
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LINKS
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FORMULA
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MATHEMATICA
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Join @@ ((FromDigits /@ Tuples[{5, 8}, #]) & /@ Range@ 5) (* Giovanni Resta, Mar 28 2017 *)
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PROG
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(Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {5, 8}]
(Python)
def a(n): return int(bin(n+1)[3:].replace('0', '5').replace('1', '8'))
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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