A121603 - OEIS

A121603

Numbers n such that the radius of the smallest circle into which n unit circles can be packed is 1 + csc(Pi/k), where k >= 2 is an integer.

2, 3, 4, 5, 6, 7, 8, 9, 11

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OFFSET

1,1

COMMENTS

Corresponding k values are in A121604. For these n, the centers of k unit circles can form a regular k-gon with sides of length 2 centered at the center of the larger circle. From the diagrams in the link it appears likely that 13,18,19 are the next three terms.

LINKS

Table of n, a(n) for n=1..9.

E. Friedman, Erich's Packing Center: "Circles in Circles"

EXAMPLE

See A121602 for the case n=11 involving a 9-gon.

CROSSREFS

Cf. A121604, A121570, A121598, A121601, A121602.

Sequence in context: A120126 A062399 A351870 * A261333 A330430 A031086

Adjacent sequences: A121600 A121601 A121602 * A121604 A121605 A121606

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Aug 09 2006

STATUS

approved