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 A304368 #16 Feb 16 2025 08:33:54
%S A304368 199,289,298,379,388,397,469,478,487,496,559,568,577,586,595,649,658,
%T A304368 667,676,685,694,739,748,757,766,775,784,793,829,838,847,856,865,874,
%U A304368 883,892,919,928,937,946,955,964,973,982,991,1099,1189,1198,1279,1288,1297
%N A304368 Numbers n with additive persistence = 3.
%C A304368 First deviation from A166459 is at a(101); a(101) = 1999, A166459(101) = 2089.
%H A304368 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/AdditivePersistence.html">Additive Persistence.</a>
%F A304368 A031286(a(n)) = 3.
%e A304368 Repeatedly taking the sum of digits starting with 199 gives 19, 10, and then 1. There are three steps, so the additive persistence is 3, and 199 is a member. - _Michael B. Porter_, May 16 2018
%t A304368 Select[Range@ 1300, Length@ FixedPointList[Total@ IntegerDigits@ # &, #] == 5 &] (* _Michael De Vlieger_, May 14 2018 *)
%o A304368 (PARI) nb(n) = {my(nba = 0); while (n > 9, n = sumdigits(n); nba++); nba;}
%o A304368 isok(n) = nb(n) == 3; \\ _Michel Marcus_, May 13 2018
%Y A304368 Cf. A031286.
%Y A304368 Cf. Numbers with additive persistence k: A304366 (k=1), A304367 (k=2), A304373 (k=4).
%K A304368 nonn,base
%O A304368 1,1
%A A304368 _Jaroslav Krizek_, May 11 2018