A307117 Numbers x that are equal to lpf(x)*gpf(x)*(lpf(x)+gpf(x))/2, where lpf(x) and gpf(x) are the least and the greatest prime factors of x: A020639 and A006530.

8, 27, 105, 125, 231, 343, 627, 897, 935, 1331, 1581, 1729, 2197, 2465, 2967, 3525, 4123, 4301, 4715, 4913, 5487, 6859, 7035, 7685, 7881, 9717, 10707, 11339, 12167, 14993, 16377, 17353, 17655, 20213, 20915, 23779, 24389, 24765, 25327, 26331, 26765, 29341, 29607

Offset

1,1

Comments

This is A307108 with terms such that lpf(x)=gpf(x), that is, with cubes of primes.

Links

Table of n, a(n) for n=1..43.

Crossrefs

Cf. A000040, A020639, A006530, A307108.

Cf. A262723 is the subsequence with terms such that lpf(x)!=gpf(x), and (lpf(x)+gpf(x))/2 a prime.

Sequence in context: A343729 A343283 A126163 * A331285 A183316 A045971

Adjacent sequences: A307114 A307115 A307116 * A307118 A307119 A307120

Keyword

nonn

Author

Alex Ratushnyak, Mar 25 2019

Status

approved