A302139 Numbers k such that A111336(k) = 4.
8, 12, 16, 20, 24, 32, 64, 120, 128, 256, 512, 600, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736
Offset: 1
Examples
For k >= 3, 2^k is a term because the four regular polytopes with 2^k faces are the 2^k-gon, the k-dimensional orthoplex, the 2^(k-1)-dimensional cube and the (2^k-1)-dimensional simplex. [Corrected by _Jianing Song_, Dec 09 2018]
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
- Wikipedia, Regular Polytopes.
- Index entries for linear recurrences with constant coefficients, signature (2).
Crossrefs
Cf. A111336.
Programs
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Mathematica
LinearRecurrence[{2},{8,12,16,20,24,32,64,120,128,256,512,600,1024},50] (* Harvey P. Dale, Jul 14 2025 *)
Formula
a(n) = 2^(n-3) for n >= 13.
Comments