OFFSET
0,18
COMMENTS
The two color classes are not interchangeable. Adjacent nodes cannot have the same color.
Essentially the same data as given in the irregular triangle A122085, but including complete columns for n = 0 and m = 0 to give a regular array.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1325
EXAMPLE
Array begins:
===================================================
n\m | 0 1 2 3 4 5 6 7 8
----+----------------------------------------------
0 | 1, 1, 0, 0, 0, 0, 0, 0, 0, ...
1 | 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
2 | 0, 1, 1, 2, 2, 3, 3, 4, 4, ...
3 | 0, 1, 2, 4, 7, 10, 14, 19, 24, ...
4 | 0, 1, 2, 7, 14, 28, 45, 73, 105, ...
5 | 0, 1, 3, 10, 28, 65, 132, 242, 412, ...
6 | 0, 1, 3, 14, 45, 132, 316, 693, 1349, ...
7 | 0, 1, 4, 19, 73, 242, 693, 1742, 3927, ...
8 | 0, 1, 4, 24, 105, 412, 1349, 3927, 10079, ...
...
PROG
(PARI)
EulerXY(A)={my(j=serprec(A, x)); exp(sum(i=1, j, 1/i * subst(subst(A + x * O(x^(j\i)), x, x^i), y, y^i)))}
R(n)={my(A=O(x)); for(j=1, 2*n, A = if(j%2, 1, y)*x*EulerXY(A)); A};
P(n)={my(r1=R(n), r2=x*EulerXY(r1), s=r1+r2-r1*r2); Vec(1 + s)}
{ my(A=P(10)); for(n=0, #A\2, for(k=0, #A\2, print1(polcoef(A[n+k+1], k), ", ")); print) }
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Andrew Howroyd, Nov 02 2019
STATUS
approved