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 A008523 Numbers that do not contain the letter 't'. 8
 0, 1, 4, 5, 6, 7, 9, 11, 100, 101, 104, 105, 106, 107, 109, 111, 400, 401, 404, 405, 406, 407, 409, 411, 500, 501, 504, 505, 506, 507, 509, 511, 600, 601, 604, 605, 606, 607, 609, 611, 700, 701, 704, 705, 706, 707, 709, 711, 900, 901, 904, 905, 906, 907, 909, 911, 1000000, 1000001, 1000004, 1000005 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS See also A006933, the eban numbers (numbers not containing 'e'), and A089589 (the iban numbers). This sequence might correspondingly be called the "tban" numbers. - WG Zeist, Aug 31 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 Roel and Bas van Dijk, Numerals package, Hackage (Haskell packages) 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 a008523 n = a008523_list !! (n-1) a008523_list = filter (T.all (/= 't') . 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 "t" 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(), 60))) # Michael S. Branicky, Aug 19 2022 CROSSREFS Cf. A006933 (ban e), A089589 (ban i), A008521 (ban o), A089590 (ban u). Sequence in context: A095033 A010399 A215046 * A047568 A139453 A010391 Adjacent sequences: A008520 A008521 A008522 * A008524 A008525 A008526 KEYWORD nonn,word AUTHOR N. J. A. Sloane EXTENSIONS a(57)-a(60) from WG Zeist, Aug 31 2012 STATUS approved

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Last modified June 4 21:12 EDT 2023. Contains 363128 sequences. (Running on oeis4.)