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 A301408 #13 May 03 2018 03:04:53 %S A301408 4,0,3,1,11,23,123,101323373373 %N A301408 Repeatedly map numbers to the number of letters in the English name (include spaces, but no hyphens and no "and"s); sequence gives smallest nonnegative integer that needs exactly n iterations to get to 4. %D A301408 M. Ecker, Number play, calculators, and card tricks: Mathemagical black holes, in E. Berlekamp and T. Rodgers, eds., The Mathemagician and Pied Puzzler: A Collection in Tribute to Martin Gardner, A. K. Peters, 1999, pp. 41-52. %e A301408 Since "twenty three" has 12 letters (including the space), "twelve" has 6 letters, "three" has 5 letters, "four" has four letters, and no other smaller nonnegative integer maps to 4 in exactly 5 iterations, then a(5) = 23. %Y A301408 Cf. A227290, A005589, A016037 (these do not count the spaces in the names of larger integers). %K A301408 nonn,word,less %O A301408 0,1 %A A301408 _Matthew E. Coppenbarger_, Mar 20 2018