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 A306949 #16 Mar 13 2021 11:06:22 %S A306949 2,2,3,3,4,3,2,2,3,2,2,1,1,2,2,2,1,3,3,4,4,3,3,4,3,2,2,2,2,3,3,3,3,2, %T A306949 2,2,2,3,3,3,3,3,3,2,2,3,3,2,2,2,1,3,3,3,3,3,3,2,2,2,2,2,2,2,3,3,3,4, %U A306949 4,4,4,3,3,3,3,4,4,4,4,4,4,4,4,1,2,2,2,2,2,2,3,4 %N A306949 a(n) is the number of different types of faces of Johnson solid J_n, with solids ordered by indices in Johnson's paper. %C A306949 A299529(x) equals the number of times the value x occurs as a term in this sequence. In particular, if A299529(x) = 0, then x does not occur in this sequence. %D A306949 V. A. Zalgaller, Convex Polyhedra with Regular Faces, in: Seminars in mathematics, Springer, 1969, ISBN 978-1-4899-5671-2. %H A306949 N. W. Johnson, <a href="https://doi.org/10.4153/CJM-1966-021-8">Convex Polyhedra with Regular Faces</a>, Canadian Journal of Mathematics 18 (1966), 169-200. %H A306949 Wikipedia, <a href="https://en.wikipedia.org/wiki/List_of_Johnson_solids">List of Johnson solids</a> %H A306949 V. A. Zalgaller, <a href="http://mi.mathnet.ru/eng/znsl1408">Convex Polyhedra with Regular Faces</a>, Zapiski Nauchnykh Seminarov LOMI 2 (1967), 5-221. %e A306949 For n = 5: Johnson solid J_5 is the pentagonal cupola. This solid is bounded by 5 equilateral triangles, 5 squares, 1 pentagon and 1 decagon. Thus, there are 4 types of polygons making up the faces of this solid, hence a(5) = 4. %Y A306949 Cf. A242731, A242732, A242733, A296603, A296604, A299529. %K A306949 nonn,fini,full %O A306949 1,1 %A A306949 _Felix Fröhlich_, Mar 17 2019 %E A306949 a(68) corrected and a(88)-a(92) added by _Pontus von Brömssen_, Mar 13 2021