42030

Appears in sequences

• Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 82.at n=4A031760
• a(n) = 25*n^2 + 5.at n=40A158445
• Square array read by antidiagonals: A(n,k) is the number of ordered solutions (x_1, x_2, ..., x_n) to equation phi(Product_{i=1..n} x_i) = k * Sum_{i=1..n} phi(x_i), or -1 if there are infinitely many solutions, n >= 1, k >= 1.at n=74A336710
• a(n) = Sum_{k=1..n} sigma(k)*sigma(2*k), where sigma(n) = A000203(n) is the sum of the divisors of n.at n=25A347108