10281600

Appears in sequences

• a(n) = (2^n - 1)*n!.at n=8A052589
• k-imperfect numbers for some k >= 1.at n=25A127724
• 3-imperfect numbers.at n=17A127726
• Triangle T(n, k, m) = f(n, m)/(f(k, m)*f(n-k, m)), where T(0, k, m) = 1, f(n, k) = Product_{j=1..n} ( j!*((k+1)^j -1)/k ), f(n, 0) = n!, and m = 1, read by rows.at n=37A156765
• Triangle T(n, k, m) = f(n, m)/(f(k, m)*f(n-k, m)), where T(0, k, m) = 1, f(n, k) = Product_{j=1..n} ( j!*((k+1)^j -1)/k ), f(n, 0) = n!, and m = 1, read by rows.at n=43A156765
• Numbers k for which sigma(k)/k - 3/7 is an integer.at n=6A218410
• Integers k such that numerator and denominator of sigma(k)/k are both prime.at n=33A247086