[seqfan] Link between A053726 and A193773.

[Allan Wechsler]

The number of representations of n as 2XY - X - Y (1 <= X <= Y) is recorded
in oeis.org/A193773.

The list of numbers of the form 2KL - K - L + 1, (2 <= K <= L) is in
oeis.org/A053726. (These are "flag numbers", where N stars can be arranged
on a flag in a K-by-L rectangle with a (K-1)-by-(L-1) rectangle
interleaved. The current flag of the USA shows that 50 is a flag number,
with K = 6 and L = 5.)

It is clear that N is in A053726 exactly when A193776(N-1) > 1.

Neither sequence currently acknowledges its relationship to the other. I'd
like to add cross-links and commentary, but I don't want to clutter up both
entries. Does anyone have advice on how to add this connection gracefully?