41789

Appears in sequences

• a(n) = 2 * A079500(n) - A079500(n+1).at n=23A188541
• Nonnegative values x of solutions (x, y) to the Diophantine equation x^2 + (x+511)^2 = y^2.at n=25A207078
• Expansion of phi(x^2) / f(-x) in powers of x where phi(), f() are Ramanujan theta functions.at n=35A226622
• Consider a non-palindromic number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that Sum_{i=1..k-1}{phi(Sum_{j=1..i}{d_(j)*10^(j-1)})} = Sum_{i=1..k-1}{phi(Sum_{j=1..i}{d_(k-j+1)*10^(i-j)})} (see example below).at n=39A241503
• Numbers k such that k![12]+2 is prime, where k![12] is the twelve-fold multifactorial.at n=38A283594
• a(n) = Sum_{1 <= x_1, x_2, x_3 <= n} gcd(x_1, x_2, n)/gcd(x_1, x_2, x_3, n).at n=31A373061