This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A008537 #31 Aug 08 2023 18:00:53 %S A008537 0,2,3,4,5,6,8,12,30,32,33,34,35,36,38,40,42,43,44,45,46,48,50,52,53, %T A008537 54,55,56,58,60,62,63,64,65,66,68,80,82,83,84,85,86,88 %N A008537 Numbers that do not contain the letter 'n'. %C A008537 From _M. F. Hasler_, Apr 01 2019: (Start) %C A008537 This sequence contains 42 nonzero terms below 10^9, plus the initial a(1) = 0. %C A008537 Since "hundred", "thousand", "million" etc. are forbidden, the only way to extend the sequence would be to use long scale with "milliard" for 10^9: then the next term would be a(44) = 2*10^9 = "two milliards", a(45) = 2*10^9 + 2, and so on. %C A008537 The 2019 "April Fools contest" on codeforces.com referred to these numbers as "Kanban numbers", i.e., numbers which ban the letters 'k', 'a' and 'n'. But no 'k' ever appears, and unless we consider "milliard", 'a' only appears (in "thousand" and later "quadrillion") in conjunction with 'n', which therefore is the only relevant. So "n-ban (or maybe: anban) numbers" would be more a adequate name. (End) %H A008537 GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See Puzzle 114, p. 56. %H A008537 Mariia Mykhailova (alias Nickolas), <a href="https://codeforces.com/contest/1145/problem/B">April Fools Day Contest 2019 - B: Kanban Numbers</a>, on codeforces.com, April 1, 2019. %o A008537 (PARI) is(n)=!setsearch(Set(Vec(English(n))),"n") \\ See A052360 for English(). - _M. F. Hasler_, Apr 01 2019 %o A008537 (Python) %o A008537 from num2words import num2words %o A008537 afull = [k for k in range(100) if "n" not in num2words(k)] %o A008537 print(afull) # _Michael S. Branicky_, Aug 18 2022 %Y A008537 Cf. A006933 (eban numbers: without 'e'), A089589 (without 'i'), A008521 (without 'o'), A089590 (without 'u'), A008523 (without 't'), A072956 (turban numbers: without r, t or u), A072957 (urban numbers: without r or u). %K A008537 nonn,word,fini,full %O A008537 1,2 %A A008537 _N. J. A. Sloane_ %E A008537 Edited by _M. F. Hasler_, Apr 01 2019