a binomial sum.

[Henry Gould]

Now that we have been from A = B to Y = Z about "closed formulas", I want to
ask pin why he is interested in the sequence 1, -1, 7, -21, 81, -295, 1107,
-4165, 15793, -60171, 230253, -884235, 3406105, -13154947, 50922987,
-197519941, 767502945, -2987013067, 11641557717, -45429853651, 177490745985,
...,
in the first place. Why is this an interesting sequence? Has it any
interesting applications?
Henry W. Gould