
EXAMPLE

Triangle A219120 begins:
1;
1, 1, 1;
1, 5, 2, 2, 1;
1, 15, 13, 19, 3, 3, 1;
1, 37, 128, 26, 74, 46, 4, 4, 1;
1, 83, 679, 755, 654, 68, 230, 90, 5, 5, 1;
1, 177, 2866, 9048, 2091, 5741, 1856, 498, 545, 155, 6, 6, 1; ...
in which the o.g.f. of row n, R(x,n), is given by:
R(x,n) = (1x)^(2*n1) * Sum_{k>=0} k^n *(k+1)^(k1) * exp((k+1)*x) * x^k/k!;
note that the coefficient of x^n in R(x,n), for n>=1, forms this sequence.
The signs of the terms of this sequence begin:
+,+,
,,,,
+,+,+,+,+,
,,,,,,,
+,+,+,+,+,+,+,+,+,+,
,,,,,,,,,,,
+,+,+,+,+,+,+,+,+,+,+,+,+,
,,,,,,,,,,,,,,
+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,
,,,,,,,,,,,,,,,,,
+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,
,,,,,,,,,,,,,,,,,,,
+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+,+, ...
