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A357077
The lesser of two consecutive numbers with at least 3 prime factors (counted with multiplicity).
1
27, 44, 63, 75, 80, 98, 99, 104, 116, 124, 125, 135, 147, 152, 153, 164, 170, 171, 174, 175, 188, 189, 195, 207, 224, 230, 231, 242, 243, 244, 245, 255, 260, 272, 275, 279, 284, 285, 296, 315, 324, 332, 342, 343, 344, 350, 351, 356, 363, 368, 369, 374, 375, 384, 387, 399
OFFSET
1,1
COMMENTS
The first of two consecutive numbers in A033942.
LINKS
EXAMPLE
27 = 3^3 and 28 = 2^2 * 7. Thus, 27 and 28 both have at least three prime factors. Thus, 27 is in this sequence.
MAPLE
R:= NULL: count:= 0: state:= 0:
for n from 1 while count < 100 do
if numtheory:-bigomega(n) >= 3 then
if state = 1 then R:= R, n-1; count:= count+1
else state:= 1
fi
else state := 0
fi
od:
R; # Robert Israel, Sep 16 2022
MATHEMATICA
Select[Range[1000], Total[Transpose[FactorInteger[#]][[2]]] >= 3 && Total[Transpose[FactorInteger[# + 1]][[2]]] >= 3 &]
PROG
(Python)
from sympy import factorint
def is033942(n): return sum(factorint(n).values()) > 2
def ok(n): return is033942(n) and is033942(n+1)
print([k for k in range(400) if ok(k)]) # Michael S. Branicky, Sep 10 2022
CROSSREFS
Sequence in context: A114446 A141229 A253919 * A259504 A307373 A121614
KEYWORD
nonn
AUTHOR
Tanya Khovanova, Sep 10 2022
STATUS
approved