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 A089590 Uban numbers (the letter u is banned from the English name of the number). 9
 0, 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89, 90, 91, 92, 93, 95, 96, 97, 98, 99 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS The sequence of uban numbers first differs from A052406 (the numbers not containing the digit 4) at the term 40 (forty), which is a uban number but is not 4-less. LINKS Daniel Arribas and Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 (first 89 terms from Daniel Arribas) Roel and Bas van Dijk, Numerals package, Hackage (Haskell packages) Eric Weisstein's World of Mathematics, Uban Number Index entries for sequences related to number of letters in n PROG (Haskell) import Data.Maybe (fromJust) import Data.Text (Text); import qualified Data.Text as T (all) import Text.Numeral.Grammar.Reified (defaultInflection) import qualified Text.Numeral.Language.EN as EN -- see link a089590 n = a089590_list !! (n-1) a089590_list = filter (T.all (/= 'u') . numeral) [0..] where numeral :: Integer -> Text numeral = fromJust . EN.gb_cardinal defaultInflection -- Reinhard Zumkeller, Jan 23 2015 (Python) from num2words import num2words from itertools import islice, product def ok(n): return "u" not in num2words(n) def agen(): # generator of terms < 10**304 base, pows = [k for k in range(1, 1000) if ok(k)], [1] yield from ([0] if ok(0) else []) + base for e in range(3, 304, 3): if "u" not in num2words(10**e)[4:]: pows = [10**e] + pows for t in product([0] + base, repeat=len(pows)): if t[0] == 0: continue yield sum(t[i]*pows[i] for i in range(len(t))) print(list(islice(agen(), 100))) # Michael S. Branicky, Aug 19 2022 CROSSREFS Cf. A052406. Cf. A006933 (ban e), A089589 (ban i), A008521 (ban o), A008523 (ban t). Sequence in context: A242410 A258022 A333638 * A052406 A022306 A183298 Adjacent sequences: A089587 A089588 A089589 * A089591 A089592 A089593 KEYWORD nonn,easy,word AUTHOR Eric W. Weisstein, Nov 09 2003 EXTENSIONS a(1) = 0 prepended by Reinhard Zumkeller, Jan 23 2015 STATUS approved

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Last modified April 16 03:28 EDT 2024. Contains 371696 sequences. (Running on oeis4.)