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%I #27 Apr 03 2023 14:33:36
%S 1,2,3,4,5,6,7,8,9,11,12,13,15,18,1001,1002,1003,1004,1005,1006,1007,
%T 1008,1009,1010,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010,
%U 3001,3002,3003,3004,3005,3006,3007,3008,3009,3010,4001,4002,4003,4004,4005,4006,4007,4008,4009,4010,5001,5002,5003,5004,5005,5006,5007,5008,5009,5010,6001,6002,6003
%N Positive numbers that, spelled in English, are as long as the spelling of their digits.
%C _Dan Hoey_ came up with an inequality Spell_Length(n)<=A*n+B (I've forgotten A and B, which are fairly small rationals: equality at two points), that was used to limit the maximum length of a self-enumerating sentence, and thus make an exhaustive search possible. - _R. H. Hardin_, Feb 22 2012
%D Eric Angelini, Posting to Sequence Fans Mailing List, Feb 12 2012
%D Hans Havermann, Posting to Sequence Fans Mailing List, Feb 23 2012
%H Hans Havermann, <a href="/A213006/b213006.txt">Table of n, a(n) for n = 1..10000</a>
%e 11 = eleven (6 letters) = one one (6 letters)
%e 1002 = one thousand two (14 letters) = one zero zero two (14 letters).
%o (Python)
%o from num2words import num2words as n2w
%o m = {"0":4, "1":3, "2":3, "3":5, "4":4, "5":4, "6":3, "7":5, "8":5, "9":4}
%o def dl(n): return sum(m[d] for d in str(n))
%o def wl(n): return sum(1 for c in n2w(n).replace(" and", "") if c.isalpha())
%o def ok(n): return dl(n) == wl(n)
%o print([k for k in range(1, 7000) if ok(k)]) # _Michael S. Branicky_, Apr 03 2023
%K nonn,base,word
%O 1,2
%A _N. J. A. Sloane_, Jun 01 2012
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