A137237 Number of non-isomorphic drawings of K_n with minimum crossings.

1, 1, 1, 1, 1, 1, 5, 3

Offset

1,7

Comments

Entry for n=9 stated to be "about 200" in reference.

The paper does not actually show the five drawings of K_7, the three drawings of K_8, or the "about 200" drawings of K_9. Nor does it explain how these numbers were arrived at, or prove that there is only one drawing for K<7.

Links

Table of n, a(n) for n=1..8.

P. Erdos and R. K. Guy, Crossing Number Problems, The American Mathematical Monthly, Vol. 80, No. 1. (1973), pp. 52-58.

Crossrefs

Sequence in context: A212481 A046270 A139207 * A369841 A152419 A322758

Adjacent sequences: A137234 A137235 A137236 * A137238 A137239 A137240

Keyword

hard,more,nonn

Author

Jonathan Schneider (jschne9(AT)uic.edu), Mar 08 2008

Status

approved