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

1,1

Comments

All terms beyond a(12) = 600 are powers of 2.

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).

Formula

a(n) = 2^(n-3) for n >= 13.

Example

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]

Mathematica

LinearRecurrence[{2}, {8, 12, 16, 20, 24, 32, 64, 120, 128, 256, 512, 600, 1024}, 50] (* Harvey P. Dale, Jul 14 2025 *)

Crossrefs

Cf. A111336.

Sequence in context: A377316 A387713 A192544 * A160392 A242272 A078609

Adjacent sequences: A302136 A302137 A302138 * A302140 A302141 A302142

Keyword

easy,nonn

Author

Jianing Song, Apr 02 2018

Status

approved