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 A380963 #13 Mar 19 2025 05:54:37 %S A380963 1,9,33,75,233,374,742,1294,2042,3029,4931,6535,9507,13214,17577, %T A380963 22762,31335,38341,49660,62791,77689,94239,119151,139727,170553, %U A380963 204832,242122,282811,340914,388834,456668,530819,609982,694982,810204,906951,1038672 %N A380963 The number of perimeter-magic pentagons of order 3 with magic sum n. %C A380963 The requirements are that there are 3 integers at each side of the pentagon (2 of them shared by adjacent sides), which sum up to n. All 10 integers on the 5 sides must be distinct. Pentagons obtained by reflections or rotations are considered to be the same. %C A380963 If the 10 integers do not need to be distinct and if solutions by rotations around the five-fold symmetry axis and flips are considered distinct, there are A244497(n-3) perimeter-magic pentagons. - _R. J. Mathar_, Mar 10 2025 %H A380963 R. J. Mathar, <a href="https://zenodo.org/records/15001365">Generating perimeter-magic polygons</a>, C++ (2025) %e A380963 for n = 14, a(14) = 1 5 %e A380963 6 7 %e A380963 3 2 %e A380963 10 8 %e A380963 1 9 4 %Y A380963 Cf. A380962 (perimeter-magic squares), A380853 (perimeter-magic triangles), A380964 (perimeter-magic hexagons). %K A380963 nonn %O A380963 14,2 %A A380963 _Derek Holton_ and Alex Holton, Feb 09 2025