909900

Appears in sequences

• The 4-tuple (2, ((2*n+1)^2-1)/2, ((2*n+3)^2-1)/2, a(n)), where a(n) = 4*(3 + 20n + 42n^2 + 32n^3 + 8n^4), has Diophantus's property that the product of any two distinct terms plus one is a square.at n=11A160372
• Number of n X n 0..5 matrices with row and column i=1..n having sum <= i*5.at n=2A213959
• T(n,k)=Number of n X n 0..k matrices with row and column i=1..n having sum <= i*k.at n=23A213962
• Number of 3X3 0..n matrices with row and column 1..3 having sum <= i*n.at n=4A213963