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A384701
On a 2 X n grid of vertices, draw a circle through every unordered triple of non-collinear vertices: a(n) is the number of distinct points where circles intersect.
4
2, 4, 18, 172, 978, 3672, 11034, 27241, 60804, 122741, 232138, 412263, 697058
OFFSET
1,1
LINKS
Scott R. Shannon, Image for a(2) = 4.
Scott R. Shannon, Image for a(3) = 18.
Scott R. Shannon, Image for a(4) = 172.
Scott R. Shannon, Image for a(5) = 978.
FORMULA
a(n) = A384703(n) - A384702(n) + 1 by Euler's formula, for n > 1.
CROSSREFS
Cf. A384700 (circles), A384702 (regions), A384703 (edges), A359569, A374825, A374338, A373106.
Sequence in context: A213793 A287612 A308755 * A318394 A228933 A347514
KEYWORD
nonn,more
AUTHOR
STATUS
approved