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

Author

Jianing Song, Aug 07 2022

Keywords

• nonn
• easy

Comments

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

Examples

			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).
		

Links

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

Crossrefs

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

Programs

PARI

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