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 A321676 #68 Mar 23 2025 17:39:47
%S A321676 1,3,5,7,9,11,14,18,22,24,27,30,31,34,37,40,41,44,47,50,51,54,57,60,
%T A321676 61,64,67,70,72,75,79,83,87,91,95,99,103,109,115,122,128,135,142,148,
%U A321676 155,162,168,175,183,191,199,207,212,217,224,230,234,240,244,250
%N A321676 a(1)=1; for n > 1, a(n) is a(n-1) plus the number of vowels in the name of a(n-1) in US English.
%C A321676 This sequence takes into account the numbers written as words; for example, "fifty-seven" contains three vowels, so 3 is added to 57 to create the next term. The word "and" is not included in US English (cf. A158352), so 115 is written as "one hundred fifteen". This sequence is puzzling as it shares its first 6 terms with the odd numbers before jumping to 14, then 18. When only given the first 8 terms it can be very difficult to spot the rule.
%C A321676 Assumes "y" in e.g. "fifty" is not a vowel. - _Chai Wah Wu_, Dec 17 2018
%F A321676 a(n) = A139282(n) for n >= 2. - _Chai Wah Wu_, Dec 17 2018
%t A321676 vowelCount[n_] := StringCount[IntegerName[n, "Words"], {"a","e","i","o","u"}]; f[n_] := n + vowelCount[n]; NestList[f, 1, 100] (* _Amiram Eldar_, Dec 10 2018 *)
%o A321676 (Python)
%o A321676 from itertools import accumulate, repeat
%o A321676 from num2words import num2words
%o A321676 A321676_list = list(accumulate(repeat(1,100), lambda x,_ : x+sum(num2words(x).count(d) for d in 'aeiou'))) # _Chai Wah Wu_, Dec 17 2018
%Y A321676 Cf. A005589, A037196, A139282, A158352.
%K A321676 nonn,word,easy
%O A321676 1,2
%A A321676 _Andrew Toothill_, Dec 02 2018
%E A321676 More terms from _Amiram Eldar_, Dec 10 2018