28521

Appears in sequences

• Number of ordered quadruples of integers from [ 1..n ] with no global factor.at n=27A015634
• Number of nonnegative integer 3 X 3 matrices with no zero rows or columns and with sum of elements equal to n.at n=10A055005
• Coefficients of 1/(Sum_{k>=0} [(k+1)*r]*(-x)^k), where r = 4^(1/3) and [ ] = floor.at n=15A288231
• Numbers n such that the sum of the divisors of n is of the form m^2+1.at n=7A289290
• p-INVERT of (1,1,0,0,0,0,...), where p(S) = 1 - S - S^2 - 2 S^3.at n=10A291410
• Number of free linear polycubes of size n, identifying rotations and reflections.at n=10A363202