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A134629
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Least nonnegative integer which requires n letters to spell in English, excluding spaces and hyphens. A right inverse of A005589.
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8
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1, 0, 3, 11, 15, 13, 17, 24, 23, 73, 101, 104, 103, 111, 115, 113, 117, 124, 123, 173, 323, 373, 1104, 1103, 1111, 1115, 1113, 1117, 1124, 1123, 1173, 1323, 1373, 3323, 3373, 11373, 13323, 13373, 17373, 23323, 23373, 73373, 101373, 103323, 103373, 111373, 113323, 113373, 117373, 123323, 123373
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OFFSET
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3,3
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COMMENTS
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LINKS
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Eric Weisstein's World of Mathematics, Number.
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EXAMPLE
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a(3) = 1: "one", a(4) = 0: "zero", a(5) = 3: "three", a(6) = 11: "eleven", a(7) = 15: "fifteen", etc.
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MATHEMATICA
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(* first load Hans Havermann's text file a001477.txt and then *)
f[n_] := Length@ Characters@ ToString@ lst[[n]]; g[n_] := Block[{k = 1}, While[ f[k] != n, k++]; k]; Array[g, 41, 3] - 1 (* Robert G. Wilson v, May 26 2013 *)
f[n_] := Length@ StringPartition[ StringReplace[ IntegerName[n, "Words"], ", " | " " | "\[Hyphen]" -> ""], 1] (* after Giovanni Resta in A005589 *); t[_] := 0; k = 1; While[k < 174000, a = f@k; If[t[a] == 0, t[a] = k]; k++]; t[4] = 0 (* only {0, 4, 5 & 9} have just four letters *); t@# & /@ Range[3, 54] (* Robert G. Wilson v, May 25 2018 *)
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PROG
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(Python)
from num2words import num2words as n2w
from itertools import count, islice
def f(n): return sum(1 for c in n2w(n).replace(" and", "") if c.isalpha())
def agen(): # generator of terms
adict, n = dict(), 3
for k in count(0):
v = f(k)
if v not in adict: adict[v] = k
while n in adict: yield adict[n]; n += 1
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CROSSREFS
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KEYWORD
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nonn,word
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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