A365270 Practical numbers that have middle divisors.

1, 2, 4, 6, 8, 12, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 48, 54, 56, 60, 64, 66, 72, 80, 84, 88, 90, 96, 100, 104, 108, 112, 120, 126, 128, 132, 140, 144, 150, 156, 160, 162, 168, 176, 180, 192, 196, 198, 200, 204, 208, 210, 216, 220, 224, 228, 234, 240, 252, 256

Offset

1,2

Comments

Very similar to A174973 from which differs at a(195) = 1014 here and 1020 there.

It appears that these are also the practical numbers k whose symmetric representation of sigma(k) has an odd number of parts.

Links

Table of n, a(n) for n=1..60.

Example

a(195) = 1014 is a practical number (A005153) and it has two middle divisors so 1014 is in the sequence.

Crossrefs

Intersection of A005153 and A071562.

Cf. A067742, A174973, A236104, A237270, A237271, A237591, A237593, A317412.

Sequence in context: A092903 A005153 A174973 * A238443 A325795 A359420

Adjacent sequences: A365267 A365268 A365269 * A365271 A365272 A365273

Keyword

nonn

Author

Omar E. Pol, Aug 30 2023

Status

approved