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A360411
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Numbers k such that k*(k+1) does not contain the digit 2.
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1
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2, 5, 7, 9, 10, 12, 17, 19, 22, 24, 25, 27, 29, 30, 32, 34, 37, 39, 40, 42, 44, 55, 57, 59, 60, 62, 64, 67, 69, 70, 74, 75, 77, 80, 82, 84, 85, 87, 89, 90, 92, 94, 97, 99, 100, 102, 105, 107, 109, 114, 115, 117, 122, 124, 125, 129, 130, 132, 134, 135, 137, 139, 140, 174, 175, 177, 182, 184, 185
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OFFSET
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1,1
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COMMENTS
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All terms == 0, 2, 4, 5, 7, or 9 (mod 10).
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LINKS
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EXAMPLE
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a(4) = 9 is a term because 9*10 = 90 does not contain the digit 2.
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MAPLE
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remove(t -> member(2, convert(t*(t+1), base, 10)), [$1..1000]);
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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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