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A008521 Numbers that do not contain the letter 'o'.

%I A008521 #24 Feb 16 2025 08:32:32
%S A008521 3,5,6,7,8,9,10,11,12,13,15,16,17,18,19,20,23,25,26,27,28,29,30,33,35,
%T A008521 36,37,38,39,50,53,55,56,57,58,59,60,63,65,66,67,68,69,70,73,75,76,77,
%U A008521 78,79,80,83,85,86,87,88,89,90,93,95,96,97,98,99,300,303,305,306,307
%N A008521 Numbers that do not contain the letter 'o'.
%C A008521 There are exactly 454 oban numbers. - _Eric W. Weisstein_, Nov 09 2003
%H A008521 Reinhard Zumkeller, <a href="/A008521/b008521.txt">Table of n, a(n) for n = 1..454</a>
%H A008521 Roel and Bas van Dijk, <a href="http://hackage.haskell.org/package/numerals">Numerals package</a>, Hackage (Haskell packages).
%H A008521 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ObanNumber.html">Oban Number</a>
%H A008521 <a href="/index/Lc#letters">Index entries for sequences related to number of letters in n</a>
%o A008521 (Haskell)
%o A008521 import Data.Maybe (fromJust)
%o A008521 import Data.Text (Text); import qualified Data.Text as T (all)
%o A008521 import Text.Numeral.Grammar.Reified (defaultInflection)
%o A008521 import qualified Text.Numeral.Language.EN as EN  -- see link
%o A008521 a008521 n = a008521_list !! (n-1)
%o A008521 a008521_list = filter (T.all (/= 'o') . numeral) [0..] where
%o A008521    numeral :: Integer -> Text
%o A008521    numeral = fromJust . EN.gb_cardinal defaultInflection
%o A008521 -- _Reinhard Zumkeller_, Jan 23 2015
%o A008521 (Python)
%o A008521 from num2words import num2words
%o A008521 afull = [k for k in range(1000) if "o" not in num2words(k)]
%o A008521 print(afull[:70]) # _Michael S. Branicky_, Aug 18 2022
%Y A008521 Cf. A006933 (ban e), A089589 (ban i), A008523 (ban t), A089590 (ban u).
%K A008521 nonn,word,fini,full
%O A008521 1,1
%A A008521 _N. J. A. Sloane_