1768448

Appears in sequences

• a(n)=2^C(n,2)*(2(4^n-n*2^n)-1).at n=5A186941
• Number of 11X2 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 11 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=23A192712