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 A352814 #15 Apr 16 2022 03:15:03 %S A352814 1,3,8,12,19,25,34 %N A352814 Solution to Forest of Numbers (Bosque de Números) puzzle if we start with the numbers 1 through n for an n X n square grid (see Comments). %C A352814 Start with an n X n square grid. Each cell has neighbors horizontally, vertically and diagonally. Place the numbers 1 to n anywhere. Now place the numbers n+1, n+2, ..., m in order, subject to the rule that when you place k, the sum of its neighbors must equal k. Then a(n) is the maximum m that can be achieved. %H A352814 Rudolfo Kurchan, <a href="http://www.puzzlefun.online">Puzzle Fun</a> %e A352814 4 X 4 solution with m = a(4) = 12 from Hector San Segundo: %e A352814 +---+---+---+---+ %e A352814 | | 10| 3 | 8 | %e A352814 +---+---+---+---+ %e A352814 | | 6| 1| 4| %e A352814 +---+---+---+---+ %e A352814 | | 2| | 5| %e A352814 +---+---+---+---+ %e A352814 | 11| 9| 7| 12| %e A352814 +---+---+---+---+ %e A352814 4 = 1 + 3, 5 = 1 + 4, 6 = 1 + 2 + 3, 7 = 2 + 5, 8 = 1 + 3 + 4, 9 = 2 + 7, 10 = 1 + 3 + 6, 11 = 2 + 9, 12 = 5 + 7. %e A352814 5 X 5 solution with m = a(5) = 19 from _Pontus von Brömssen_: %e A352814 +---+---+---+---+---+ %e A352814 | 5| 6| 7| 8| 18| %e A352814 +---+---+---+---+---+ %e A352814 | 11| | 1| | 10| %e A352814 +---+---+---+---+---+ %e A352814 | 14| | 19| 2| 16| %e A352814 +---+---+---+---+---+ %e A352814 | | 3| 9| 4| | %e A352814 +---+---+---+---+---+ %e A352814 | 15| 12| | 13| 17| %e A352814 +---+---+---+---+---+ %e A352814 . %e A352814 One of 10 6 X 6 solutions (up to rotations and reflections) with m = a(6) = 25 from _Pontus von Brömssen_, Apr 15 2022: %e A352814 +---+---+---+---+---+---+ %e A352814 | 22| 1| 15| 19| | 20| %e A352814 +---+---+---+---+---+---+ %e A352814 | 7| 14| | | 4| 16| %e A352814 +---+---+---+---+---+---+ %e A352814 | | 6| | 21| | 12| %e A352814 +---+---+---+---+---+---+ %e A352814 | 17| | 9| | 8| 25| %e A352814 +---+---+---+---+---+---+ %e A352814 | | 11| | 3| 5| | %e A352814 +---+---+---+---+---+---+ %e A352814 | 24| 13| 2| 10| 18| 23| %e A352814 +---+---+---+---+---+---+ %e A352814 . %e A352814 a(7) = 34 from Giorgio Vecchi. %Y A352814 Cf. A350627. %K A352814 nonn,more %O A352814 1,2 %A A352814 _Rodolfo Kurchan_, Apr 04 2022 %E A352814 a(6) corrected by _Pontus von Brömssen_, Apr 15 2022