OFFSET
1,2
FORMULA
a(n) = A053990(n) / 4. - Sean A. Irvine, Feb 19 2022
MATHEMATICA
With[{upto=500}, Select[Union[(#[[1]](#[[1]]+1)#[[2]](#[[2]]+1))/4&/@ Subsets[ Range[0, Floor[upto/2]], {2}]], #<=upto&]] (* Harvey P. Dale, Jan 15 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Stuart M. Ellerstein (ellerstein(AT)aol.com), Apr 22 2000
EXTENSIONS
More terms from James A. Sellers, Apr 22 2000
STATUS
approved