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 A355015 #28 Feb 16 2023 12:09:47 %S A355015 1,2,3,7,23,719,1169951 %N A355015 The least integer with cost n, using the cost function used in sequence A354914. %C A355015 The values up to 1169951 were computed by Joseph DeVincentis, Stan Wagon, and Al Zimmermann. The values appear to rise roughly quadratically, so the next one might be near 10^12 and impossible to find. It is known that the sequence is infinite: that is, the cost function is not bounded. %e A355015 Example: a(4) = 23 because 23 can be reached by the path 1, 2, 3, 4, 5, 20, 23, which has 4 addition steps, and one can check that each smaller number has cost at most 3. %Y A355015 Cf. A354914. %K A355015 nonn,hard,more %O A355015 0,2 %A A355015 _Stan Wagon_, Joseph DeVincentis, and _Al Zimmermann_, Jun 15 2022 %E A355015 a(6) corrected by _Stan Wagon_, Feb 15 2023