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 A274973 #34 Feb 18 2024 15:10:20
%S A274973 1,13,55,139,277,481,763,1135,1609,2197,2911,3763,4765,5929,7267,8791,
%T A274973 10513,12445,14599,16987,19621,22513,25675,29119,32857,36901,41263,
%U A274973 45955,50989,56377,62131,68263,74785,81709,89047,96811,105013,113665,122779,132367
%N A274973 Centered cubohemioctahedral numbers: a(n) = 2*n^3+9*n^2+n+1.
%C A274973 A faceting of the cuboctahedron, sharing the same square faces. The cubohemioctahedron has the same edge and vertex arrangement as the cuboctahedron. Beginning with the fourth term, the eight tetrahedral faces are each now "missing" a tetrahedron of size 1,4,10,20,35...(A000292). See A274974 centered octahemioctahedron for similar cuboctahedral faceting but with the square faces "missing."
%H A274973 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cubohemioctahedron">Cubohemioctahedron</a>
%H A274973 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A274973 a(n) = 2*n^3+9*n^2+n+1.
%F A274973 G.f.: (-7*x^3+9*x^2+9*x+1)/(x-1)^4.
%t A274973 Table[2 n^3 + 9 n^2 + n + 1, {n, 40}] (* _Michael De Vlieger_, Jul 13 2016 *)
%t A274973 LinearRecurrence[{4,-6,4,-1},{1,13,55,139},40] (* _Harvey P. Dale_, Feb 18 2024 *)
%o A274973 (PARI) a(n)=2*n^3+9*n^2+n+1 \\ _Charles R Greathouse IV_, Jul 14 2016
%Y A274973 Cf. A005902 (centered cuboctahedral numbers), A274974 (centered octahemioctahedral numbers).
%K A274973 nonn,easy
%O A274973 0,2
%A A274973 _Steven Beard_, Jul 13 2016