328320

Appears in sequences

• Number of n X n symmetric matrices each of whose rows is a permutation of 1..n.at n=6A035482
• Number of (2n) X (2n) symmetric matrices each of whose rows is a permutation of 1..(2n).at n=3A036980
• Numbers k such that sigma(k+1) = 5*phi(k).at n=24A067263
• a(n) = n!*Sum_{k=1..n} mu(k)/k, where mu(k) is the Möbius function.at n=9A068337
• Numbers m with property that m-th triangular number is a sum of divisors of some k-th triangular number (A175849).at n=27A175850
• Number of integers k^5 that divide 1!*2!*3!*...*n!.at n=20A248823