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 A308259 #21 Aug 21 2023 13:59:05 %S A308259 3,6,720,5043,151,122,5,120,4,24,26,722,5044,169,363601,1454,169, %T A308259 363601,1454,169,363601,1454,169,363601,1454,169,363601,1454,169, %U A308259 363601,1454,169,363601,1454,169,363601,1454,169,363601,1454,169,363601,1454,169,363601 %N A308259 a(n) is equal to the sum of the factorials of the digits of a(n-1), initial term is 3. %C A308259 From a(14) = 169, the sequence is stuck in the loop 363601, 1454, 169, 363601, 1454, ... %H A308259 Shoei Takahashi, Unchone Lee, Hikaru Manabe, Aoi Murakami, Daisuke Minematsu, Kou Omori, and Ryohei Miyadera, <a href="https://arxiv.org/abs/2308.06691">Curious Properties of Iterative Sequences</a>, arXiv:2308.06691 [math.GM], 2023. %e A308259 a(5) = 151, so a(6) = 1! + 5! + 1! = 1 + 120 + 1 = 122. %t A308259 NestList[Total@ Map[Factorial, IntegerDigits[#]] &, 3, 36] (* _Michael De Vlieger_, Aug 21 2023 *) %Y A308259 Cf. A061602, A306955. %K A308259 base,easy,nonn %O A308259 1,1 %A A308259 _Romain Pinot_, May 17 2019