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A133491 Order of the symmetry group of the (in some cases conjectural) minimal-energy configuration of n identical charged particles confined to the surface of a sphere. 2
12, 24, 12, 48, 20, 16, 12, 16, 4, 120, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

a(0), a(1) and a(2) are all infinite, because their symmetry groups are continuous (they contain rotations with arbitrary angles). Actual symmetry groups: 3 D_{3h}, 4 T_{d}, 5 D_{3h}, 6 O_{d}, 7 D_{5h}, 8 D_{4d}, 9 D_{3h}, 10 D_{4h}, 11 D_{1h}, 12 I_{d}, 13 D_{1h}.

LINKS

Table of n, a(n) for n=3..13.

K. S. Brown, Min-Energy Configurations of Electrons On A Sphere, MathPages.

R. H. Hardin, N. J. A. Sloane and W. D. Smith, Minimal Energy Configurations of Points on a Sphere

Wikipedia, Thomson Problem.

EXAMPLE

a(3)=12 because the minimal-energy configuration of 3 charged particles on a sphere is an equilateral triangle on the equator, which has symmetry group D_3h of order 12.

CROSSREFS

Cf. A033177, A242617.

Sequence in context: A072822 A239656 A059161 * A075606 A183192 A117320

Adjacent sequences:  A133488 A133489 A133490 * A133492 A133493 A133494

KEYWORD

nonn,more

AUTHOR

Keenan Pepper, Nov 30 2007

STATUS

approved

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Last modified June 24 18:46 EDT 2021. Contains 345419 sequences. (Running on oeis4.)