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A102490
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Numbers in base-16 representation that cannot be written with decimal digits.
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6
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10, 11, 12, 13, 14, 15, 26, 27, 28, 29, 30, 31, 42, 43, 44, 45, 46, 47, 58, 59, 60, 61, 62, 63, 74, 75, 76, 77, 78, 79, 90, 91, 92, 93, 94, 95, 106, 107, 108, 109, 110, 111, 122, 123, 124, 125, 126, 127, 138, 139, 140, 141, 142, 143, 154, 155, 156, 157, 158, 159, 160
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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EXAMPLE
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42 = 2*16^1 + 10*16^0 = '2A', therefore 42 is a term.
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MATHEMATICA
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Select[Range[200], IntegerLength[Max[IntegerDigits[#, 16]]]>1&] (* Harvey P. Dale, Jun 12 2020 *)
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PROG
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(Haskell)
import Data.List (unfoldr)
a102490 n = a102490_list !! (n-1)
a102490_list = filter (any (> 9) . unfoldr
(\x -> if x == 0 then Nothing else Just $ swap $ divMod x 16)) [0..]
(Python)
def ok(n): return any(hd > '9' for hd in hex(n)[2:])
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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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