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A160234
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Number of n-digit "early bird numbers" A116700.
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0
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(1) = 0 because there are no 1-digit terms in A116700;
a(1) = 45 because there are 45 2-digit terms in A116700: 12, 21, 23, 31, 32, 34, 41, 42, 43, 45, 51, 52, 53, 54, 56, 61, 62, 63, 64, 65, 67, 71, 72, 73, 74, 75, 76, 78, 81, 82, 83, 84, 85, 86, 87, 89, 91, 92, 93, 94, 95, 96, 97, 98, 99.
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MATHEMATICA
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s="1"; ss={}; Do[tsn=ToString[n]; If[ !StringFreeQ[s, tsn], AppendTo[ss, n]]; s=s<>tsn, {n, 2, 99999}]; Table[Length[Select[ss, 10^(n-1)<=#<10^n&]], {n, 1, 5}]
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PROG
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(Python)
from itertools import count, islice
def agen(): # generator of terms
s = ""
for digits in count(1):
c = 0
for k in range(10**(digits-1), 10**digits):
sk = str(k)
if sk in s: c += 1
s += sk
yield c
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CROSSREFS
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Cf. A116700 ("Early bird" numbers).
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KEYWORD
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base,nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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