a(n) is the number of times that sums 1+-4+-9+-16+-...+-n^2 of the first n squares is zero. There are 2^(n-1) choices for the sign patterns.

A083527

a(n) is the number of times that sums 1+-4+-9+-16+-...+-n^2 of the first n squares is zero. There are 2^(n-1) choices for the sign patterns.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =1a(8) =0a(9) =0a(10) =1a(11) =5a(12) =0a(13) =0a(14) =43a(15) =57a(16) =0a(17) =0a(18) =239a(19) =430a(20) =0a(21) =0a(22) =2904a(23) =5419a(24) =0a(25) =0a(26) =27813a(27) =50213a(28) =0a(29) =0

External references