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A346207 Numbers k such that k and k+1 are products of at least 6 primes. 0
1215, 3968, 5103, 5264, 6560, 7424, 7695, 8991, 9375, 9800, 11024, 11583, 11744, 12375, 12879, 13040, 14175, 14336, 14624, 15624, 16064, 16280, 16767, 16928, 17199, 17576, 18224, 21375, 21735, 22112, 22599, 22815, 23408, 24255, 24543, 24704, 24975, 25839, 26000, 26487, 27135 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Integers k such that k and k+1 are in A046305.

LINKS

Table of n, a(n) for n=1..41.

EXAMPLE

1215 = 3^5*5 is a product of 6 primes. The next integer, 1216 = 2^6*19, is a product of 7 primes. Thus, 1215 is in this sequence.

MAPLE

q:= n-> andmap(x-> numtheory[bigomega](x)>5, [n, n+1]):

select(q, [$1..30000])[];  # Alois P. Heinz, Jul 10 2021

MATHEMATICA

Select[Range[100000], Total[Transpose[FactorInteger[#]][[2]]] >= 6 && Total[Transpose[FactorInteger[# + 1]][[2]]] >= 6 &]

PROG

(Python)

from sympy import factorint

def prod6(n): return sum(factorint(n).values()) >= 6

def aupto(lim): return [k for k in range(lim+1) if prod6(k) and prod6(k+1)]

print(aupto(27135)) # Michael S. Branicky, Jul 10 2021

(PARI) isA346207(k) = (bigomega(k) >= 6) && (bigomega(k+1) >= 6) \\ Jianing Song, Jul 10 2021

CROSSREFS

Cf. A046305, A345744.

Sequence in context: A252125 A251815 A130680 * A068783 A331625 A235889

Adjacent sequences:  A346204 A346205 A346206 * A346208 A346209 A346210

KEYWORD

nonn

AUTHOR

Tanya Khovanova, Jul 10 2021

STATUS

approved

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Last modified May 19 12:20 EDT 2022. Contains 353833 sequences. (Running on oeis4.)