A097620 Numbers having more prime factors than their neighbors together.

12, 16, 18, 24, 30, 32, 36, 40, 42, 48, 54, 60, 64, 72, 84, 88, 90, 96, 102, 108, 112, 120, 128, 132, 138, 140, 144, 150, 156, 160, 162, 168, 180, 192, 198, 200, 210, 216, 224, 228, 234, 240, 250, 252, 256, 264, 270, 272, 280, 282, 288, 294, 300, 304, 306, 308

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Formula

{k: A001222(k) > A001222(k-1) + A001222(k+1)}. - Michael S. Branicky, Dec 16 2021

Example

A001222(64) = A001222(2^6) = 6, A001222(64-1) = A001222(3*3*7) = 3, A001222(64+1) = A001222(5*13) = 2, and 6 > 3+2, therefore 64 is a term.

Prog

(Python)
from sympy import primeomega
def ok(n): return primeomega(n) > primeomega(n-1) + primeomega(n+1)
print([k for k in range(2, 309) if ok(k)]) # Michael S. Branicky, Dec 16 2021

Crossrefs

Subsequence of A097619.

Cf. A001222.

Sequence in context: A107308 A051518 A043544 * A335222 A356863 A112548

Adjacent sequences: A097617 A097618 A097619 * A097621 A097622 A097623

Keyword

nonn

Author

Reinhard Zumkeller, Aug 17 2004

Status

approved