73872

Appears in sequences

• Integers k such that k + phi(k) + phi(phi(k)) is a fourth power.at n=17A116041
• Values of n*d(k)*sopf(k) associated with A134382.at n=26A134386
• a(n) = ( (6 + sqrt(6))^n - (6 - sqrt(6))^n )/(2*sqrt(6)).at n=5A154237
• Numbers with prime factorization pq^4r^5.at n=13A190468
• Composite numbers n such that Sum_{d_<n | n} phi(d_<n) / (d_<n) is an integer, where d_<n = divisors of n that are less than n, phi(x) = A000010(x).at n=43A211778
• Number of nX4 0..1 arrays with every element unequal to 0, 1, 3 or 8 king-move adjacent elements, with upper left element zero.at n=16A304217
• a(n) is the sum of lattice points enumerated by the square number spiral falling on the circumference of circles centered at the origin of radii n.at n=45A309573
• Numbers with an even number of prime factors (counted with multiplicity) that can be factored into squarefree semiprimes (A320911) but cannot be factored into distinct semiprimes (A320892).at n=23A320893
• Number of degree-n odd permutations of order dividing 12.at n=9A326242
• a(0) = 0; a(n) = ( (n + sqrt(n))^n - (n - sqrt(n))^n )/(2 * sqrt(n)).at n=6A360766