Number of permutations p of [n] satisfying Sum_{i=1..n} (p(i)-i)^2 = n*(n+1)/2.

Terms

a(0) =1a(1) =0a(2) =0a(3) =2a(4) =2a(5) =0a(6) =0a(7) =78a(8) =380a(9) =0a(10) =0a(11) =43106a(12) =230894a(13) =0a(14) =0a(15) =46470939a(16) =295990436a(17) =0a(18) =0a(19) =93486183164a(20) =677977634271a(21) =0a(22) =0a(25) =0a(26) =0a(29) =0a(30) =0