510152domain: NAppears in sequencesNumber of essentially different permutations of the numbers 1 to n such that the sum of adjacent numbers is a square.at n=27A090460Number of (1+1)X(n+1) 0..2 arrays x(i,j) with row sums sum{j*x(i,j), j=1..n+1} nondecreasing, and column sums sum{i^2*x(i,j), i=1..1+1} nondecreasing.at n=14A233050