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A107433
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Slowest increasing sequence where some digit of a(n) and some digit of a(n+1) add up to 9.
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2
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0, 9, 10, 18, 19, 20, 27, 28, 31, 36, 37, 42, 45, 46, 50, 54, 55, 64, 65, 73, 76, 82, 87, 91, 98, 100, 108, 109, 110, 118, 119, 120, 127, 128, 129, 130, 136, 137, 138, 139, 140, 145, 146, 148, 149, 150, 154, 155, 158, 159, 160, 163, 164, 165, 168, 169, 170, 172, 173
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OFFSET
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0,2
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COMMENTS
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Starting with another "seed" than 0 would produce another sequence.
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LINKS
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EXAMPLE
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After 28 we must have an integer containing a "7" (2+"7"=9) or a "1" (8+"1"=9). The smallest integer satisfying this constraint is 31 (and not 37 or 41 or any other containing a "7" or a "1")
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MAPLE
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f:= proc(n) local S, k;
S:= map(t -> 9-t, convert(convert(n, base, 10), set));
for k from n+1 do
if convert(convert(k, base, 10), set) intersect S <> {} then return k fi
od
end proc:
a[0]:= 0:
for n from 1 to 100 do a[n]:= f(a[n-1]) od:
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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