OFFSET
0,5
COMMENTS
The Errera graph is a planar graph on 17 vertices and 45 edges with chromatic number 4.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
Marc Timme, Frank van Bussel, Denny Fliegner, and Sebastian Stolzenberg, Counting complex disordered states by efficient pattern matching: chromatic polynomials and Potts partition functions, New J. Phys. 11 023001 (2009).
Eric Weisstein's World of Mathematics, Errera Graph.
Eric Weisstein's World of Mathematics, Chromatic Polynomial.
Index entries for linear recurrences with constant coefficients, signature (18, -153, 816, -3060, 8568, -18564, 31824, -43758, 48620, -43758, 31824, -18564, 8568, -3060, 816, -153, 18, -1).
FORMULA
a(n) = n^17 - 45*n^16 + ... (see Maple program).
MAPLE
a:= n-> n^17 -45*n^16 +960*n^15 -12900*n^14 +122327*n^13 -868834*n^12 +4785355*n^11 -20863215*n^10 +72791543*n^9 -203886157*n^8 +456534224*n^7 -807157880*n^6 +1101393064*n^5 -1116652249*n^4 +788961246*n^3 -344673280*n^2 +69525840*n:
seq(a(n), n=0..20);
MATHEMATICA
a[n_] := n^17 - 45*n^16 + 960*n^15 - 12900*n^14 + 122327*n^13 - 868834*n^12 + 4785355*n^11 - 20863215*n^10 + 72791543*n^9 - 203886157*n^8 + 456534224*n^7 - 807157880*n^6 + 1101393064*n^5 - 1116652249*n^4 + 788961246*n^3 - 344673280*n^2 + 69525840*n; Table[a[n], {n, 0, 10}] (* G. C. Greubel, May 29 2016 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Oct 25 2009
STATUS
approved