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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.

User: Matt Moir

Matt Moir's wiki page.

Matt Moir has authored 1 sequences.

A364922 a(n) is the square of the side length of a simplex whose n-dimensional inner hypervolume is equal to its (n-1)-dimensional surface hypervolume. As a result, the sequence starts at n=2.

Original entry on oeis.org

48, 216, 640, 1500, 3024, 5488, 9216, 14580, 22000, 31944, 44928, 61516, 82320, 108000, 139264, 176868, 221616, 274360, 336000, 407484, 489808, 584016, 691200, 812500, 949104, 1102248, 1273216, 1463340, 1674000, 1906624, 2162688, 2443716, 2751280, 3087000
Offset: 2

Author

Matt Moir, Apr 13 2024

Keywords

Comments

Setting the generalized hypervolume formula equal to the surface hypervolume formula and solving for the side length x (and ignoring the x = 0 solution, as it would correspond to a simplex consisting of only a single point) gives x = sqrt(2*(n^3)*(n+1)).

Crossrefs

Programs

  • Mathematica
    Table[2*n^3*(n + 1), {n, 2, 50}] (* Paolo Xausa, Apr 18 2024 *)
    LinearRecurrence[{5,-10,10,-5,1},{48,216,640,1500,3024},40] (* Harvey P. Dale, Aug 27 2024 *)
  • Python
    def a(n): return 2 * n**3 * (n + 1)
    print([a(n) for n in range(2, 50)])

Formula

a(n) = 2*n^3*(n+1) = 2*A179824(n+1).
From Stefano Spezia, Apr 13 2024: (Start)
G.f.: 4*x^2*(12 - 6*x + 10*x^2 - 5*x^3 + x^4)/(1 - x)^5.
a(n) = 4*A019582(n+1). (End)