9009000

Appears in sequences

• Four numbers (a,b,c,d) with a<b<c<d that satisfy sigma(a) = sigma(b) = sigma(c) = sigma(d) = a+b+c+d are called an amicable quadruple. We order these quadruples according to the common value of sigma. The values of (a, b, c, d, sigma) are in (this sequence, A036472, A036473, A036474, A116148) respectively.at n=22A036471
• a(n) = n^3*(n^3 + 1)*(n-1).at n=10A037251
• n*(n-1)*(n-2)*(n-3)*(n-4)*(2*n-1)/72.at n=28A055504
• One-sixth of the area of some primitive Heronian triangles with a distance of 2n+1 between the median and altitude points on the longest side.at n=21A074076
• Numbers with exactly two distinct base-10 digits that have more divisors than any smaller such number.at n=23A384969