Robbins numbers: a(n) = Product_{k=0..n-1} (3k+1)!/(n+k)!; also the number of descending plane partitions whose parts do not exceed n; also the number of n X n alternating sign matrices (ASM's).
A005130
Robbins numbers: a(n) = Product_{k=0..n-1} (3k+1)!/(n+k)!; also the number of descending plane partitions whose parts do not exceed n; also the number of n X n alternating sign matrices (ASM's).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =7a(4) =42a(5) =429a(6) =7436a(7) =218348a(8) =10850216a(9) =911835460a(10) =129534272700
External references
- oeis: A005130