The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A298445 Triangle T(n,k) read by rows: number of n-node simple graphs with rectilinear crossing number k (k=0..A014540(n)). 1
 1, 2, 4, 11, 33, 1, 142, 12, 1, 1, 822, 162, 39, 16, 1, 2, 1, 0, 0, 1, 6966, 3183, 1291, 559, 172, 82, 48, 12, 15, 8, 4, 1, 3, 0, 0, 1, 0, 0, 0, 1, 79853 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Computed up to n=8 using data provided by Geoffrey Exoo. (There appear to be some problems with n=9 data.) LINKS Eric Weisstein's World of Mathematics, Rectilinear Crossing Number Eric Weisstein's World of Mathematics, Simple Graph FORMULA T(n,0) = A005470(n). T(n,1) = A307071(n). kmax(n) = A014540(n). T(n,kmax(n)) = 1 for n > 4. Sum_{k=0..kmax(n)} T(n,k) = A000088(n). EXAMPLE Triangle begins: 1 2 4 11 33, 1 142, 12, 1, 1 822, 162, 39, 16, 1, 2, 1, 0, 0, 1 6966, 3183, 1291, 559, 172, 82, 48, 12, 15, 8, 4, 1, 3, 0, 0, 1, 0, 0, 0, 1 CROSSREFS Cf. A014540 (rectilinear crossing number for K_n). Cf. A298446 (counts for simple connected graphs). Cf. A307071 (number of simple graphs with crossing number 1). Sequence in context: A123449 A123404 A178925 * A294224 A296270 A123439 Adjacent sequences:  A298442 A298443 A298444 * A298446 A298447 A298448 KEYWORD nonn,tabf AUTHOR Eric W. Weisstein, Jan 19 2018 EXTENSIONS Corrected by Eric W. Weisstein, Mar 28 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 3 22:32 EST 2021. Contains 349468 sequences. (Running on oeis4.)