A356441 Numbers k such that A309892(k) < k/gpf(k), where gpf = A006530; complement of A356438.

8, 16, 18, 24, 27, 32, 36, 40, 45, 48, 50, 54, 60, 64, 72, 75, 80, 81, 84, 90, 96, 98, 100, 105, 108, 112, 120, 125, 126, 128, 135, 140, 144, 147, 150, 154, 160, 162, 165, 168, 175, 176, 180, 189, 192, 196, 198, 200, 210, 216, 220, 224, 225, 231, 234, 240, 242, 243

Offset

1,1

Comments

k is a term if and only if k/gpf(k) > nextprime(gpf(k)), where nextprime = A151800.

Links

Jianing Song, Table of n, a(n) for n = 1..13098 (all terms <= 50000)

Example

8 is a term since the number of steps needed to reach 0 of the iteration x -> x - gpf(x) starting at 8 is 3: 8 -> 6 -> 3 -> 0, and 3 < 8/gpf(8).

Prog

(PARI) isA356441(n) = if(n>1, my(p=vecmax(factor(n)[, 1])); n/p>nextprime(p+1), 0)

Crossrefs

Cf. A356438, A309892, A006530 (gpf), A151800, A076563.

Sequence in context: A101766 A338930 A357002 * A140270 A257225 A092456

Adjacent sequences: A356438 A356439 A356440 * A356442 A356443 A356444

Keyword

nonn,easy

Author

Jianing Song, Aug 07 2022

Status

approved