

A298446


Triangle T(n,k) read by rows: number of nnode connected graphs with rectilinear crossing number k (k=0..A014540(n)).


1



1, 1, 2, 6, 20, 1, 99, 11, 1, 1, 646, 149, 38, 15, 1, 2, 1, 0, 0, 1, 5974, 3008, 1251, 542, 171, 80, 47, 12, 15, 7, 4, 1, 3, 0, 0, 1, 0, 0, 0, 1, 71885
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OFFSET

1,3


COMMENTS

Computed up to n=8 using data provided by Geoffrey Exoo. (There appear to be some problems with n=9 data.)
T(9,1) >= 71335.  Eric W. Weisstein, Mar 28 2019


LINKS

Table of n, a(n) for n=1..41.
Eric Weisstein's World of Mathematics, Connected Graph
Eric Weisstein's World of Mathematics, Rectilinear Crossing Number


FORMULA

T(n,0) = A003094(n).
kmax(n) = A014540(n).
T(n,kmax(n)) = 1 for n > 4.
sum(k=0..kmax(n), T(n,k)) = A001349(n).


EXAMPLE

Triangle begins:
1
1
2
6
20,1
99,11,1,1
646,149,38,15,1,2,1,0,0,1
5974,3008,1251,542,171,80,47,12,15,7,4,1,3,0,0,1,0,0,0,1


CROSSREFS

Cf. A014540 (rectilinear crossing number for K_n).
Cf. A298445 (counts for simple graph).
Sequence in context: A332406 A127942 A110956 * A205012 A254120 A286426
Adjacent sequences: A298443 A298444 A298445 * A298447 A298448 A298449


KEYWORD

nonn,tabf


AUTHOR

Eric W. Weisstein, Jan 19 2018


EXTENSIONS

Corrected by Eric W. Weisstein, Mar 28 2019


STATUS

approved



