1368900

Appears in sequences

• First differences of A069473.at n=21A069474
• Refactorable numbers k such that the number of odd divisors r is odd, the number of even divisors s is even and both r and s are divisors of k.at n=16A120349
• Perfect squares that are a product of two distinct triangular numbers.at n=12A169836
• Number of nX2 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1.at n=11A204078
• Areas of primitive Heronian triangles K which are perfect squares.at n=27A248108
• Number of (n+2)X(2+2) 0..1 arrays with no 3x3 subblock diagonal sum equal to the antidiagonal sum or central row sum less than the central column sum.at n=7A257355
• Numbers k with the property that it is possible to write the base 2 expansion of k as concat(a_2,b_2), with a_2>0 and b_2>0 such that, converting a_2 and b_2 to base 10 as a and b, we have (a+b)^2 = k.at n=32A258844
• a(n) is the hafnian of a symmetric Toeplitz matrix M(2*n) whose first row consists of prime(2*n), prime(2*n-1), ..., prime(1).at n=4A356484