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A164791 a(n) is the smallest nonnegative number whose American English name has the letter "n" in the n-th position.

%I A164791 #21 Apr 21 2023 11:37:54
%S A164791 9,1,9,20,7,11,15,13,17,47,27,77,109,120,107,111,115,113,117,147,127,
%T A164791 177,327,377,1120,1107,1111,1115,1113,1117,1147,1127,1177,1327,1377,
%U A164791 3327,3377,11377,13327,13377,17377,23327,23377,73377,101377,103327,103377
%N A164791 a(n) is the smallest nonnegative number whose American English name has the letter "n" in the n-th position.
%D A164791 GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.
%e A164791 a(1)=9 ("Nine"), a(2)=1 ("oNe"), a(3)=9 ("niNe"), a(4)=20 ("tweNty").
%o A164791 (Python)
%o A164791 from num2words import num2words
%o A164791 from itertools import count, islice
%o A164791 def n2w(n):
%o A164791   return "".join(c for c in num2words(n).replace(" and", "") if c.isalpha())
%o A164791 def a(n):
%o A164791     return next(i for i in count(0) if len(w:=n2w(i))>=n and w[n-1]=="n")
%o A164791 print([a(n) for n in range(1, 41)]) # _Michael S. Branicky_, Apr 21 2023
%o A164791 (Python) # faster for initial segment of sequence; uses n2w, imports above
%o A164791 def agen(): # generator of terms
%o A164791     adict, n = dict(), 1
%o A164791     for i in count(0):
%o A164791         w = n2w(i)
%o A164791         if "n" in w:
%o A164791             locs = [i+1 for i, c in enumerate(w) if w[i] == "n"]
%o A164791             for v in locs:
%o A164791                 if v not in adict: adict[v] = i
%o A164791         while n in adict: yield adict[n]; n += 1
%o A164791 print(list(islice(agen(), 50))) # _Michael S. Branicky_, Apr 21 2023
%Y A164791 Cf. A164789 ("o"), A164790 ("e"), A164792 ("t"), A164793 ("i"), A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").
%K A164791 nonn,word
%O A164791 1,1
%A A164791 _Claudio Meller_, Aug 26 2009
%E A164791 a(25) and beyond from _Michael S. Branicky_, Mar 25 2021
%E A164791 Definition clarified by _N. J. A. Sloane_, Apr 20 2023. We also need a British English analog of this, just as A362121 is an analog of A164790 (a(13) will be different).