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A128422 Projective plane crossing number of K_{4,n}. +0
5
0, 0, 0, 2, 4, 6, 10, 14, 18, 24, 30, 36, 44, 52, 60, 70, 80, 90, 102, 114, 126, 140, 154, 168, 184, 200, 216, 234, 252, 270, 290, 310, 330, 352, 374, 396, 420, 444, 468, 494, 520, 546, 574, 602, 630, 660, 690, 720, 752, 784, 816, 850, 884, 918, 954, 990, 1026 (list; graph; listen)
OFFSET

1,4

COMMENT

Also, a(n) = floor((n - 1)(n - 2) / 3) for n >= 1.

LINKS

Eric Weisstein's World of Mathematics, Projective Plane Crossing Number

FORMULA

Floor[n/3](2n-3(1+Floor[n/3]))

CROSSREFS

Sequence in context: A100143 A059254 A024518 this_sequence A098380 A007782 A035501

Adjacent sequences: A128419 A128420 A128421 this_sequence A128423 A128424 A128425

KEYWORD

nonn

AUTHOR

Eric Weisstein (eric(AT)weisstein.com), Mar 02, 2007

EXTENSIONS

Comment added by Christopher Hunt Gribble (chris.eveswell(AT)virgin.net), Oct 13 2009

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Last modified December 1 19:22 EST 2009. Contains 167811 sequences.


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