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A116453
Third smallest number with exactly n prime factors.
9
5, 9, 18, 36, 72, 144, 288, 576, 1152, 2304, 4608, 9216, 18432, 36864, 73728, 147456, 294912, 589824, 1179648, 2359296, 4718592, 9437184, 18874368, 37748736, 75497472, 150994944, 301989888, 603979776, 1207959552, 2415919104
OFFSET
1,1
COMMENTS
Smallest term in A116451 having exactly n prime factors;
a(n) = A116451(A116454(n)) = A116454(n) + 2 * n + 3;
a(n) = A005010(n-2) for n > 1.
EXAMPLE
a(1) = 5 = A000040(3) > A000040(2) = 3 > A000040(1) = 2;
a(2) = 9 = A001358(3) > A001358(2) = 6 > A001358(1) = 4;
a(3) = 18 = A014612(3) > A014612(2) = 12 > A014612(1) = 8;
a(4) = 36 = A014613(3) > A014613(2) = 24 > A014613(1) = 16.
PROG
(Python)
def A116453(n): return 9<<n-2 if n>1 else 5 # Chai Wah Wu, Aug 23 2024
CROSSREFS
Sequence in context: A110349 A036832 A257595 * A046578 A046590 A372997
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 16 2006
STATUS
approved