320400

Appears in sequences

• Triangular numbers which are 9-almost primes.at n=7A076583
• Triangular numbers for which the sum of the digits is a square.at n=36A117404
• Triangular numbers that are the product of a square number and a prime number.at n=28A253653
• Refactorable triangular numbers.at n=36A272524
• a(n) = n^2*(2*n^2 + (-1)^n).at n=20A275496
• Coreful triperfect numbers: numbers k such that csigma(k) = 3*k, where csigma(k) is the sum of the coreful divisors of k (A057723).at n=25A364990
• Triangular numbers such that the three numbers before it and the three numbers after it are squarefree.at n=20A374393
• Triangular numbers whose sum of digits is 9.at n=24A375824
• Sum of the orders of the automorphism groups for every group of order n.at n=53A385480