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A120927
a(n) = floor(semiprime(n)/n).
2
4, 3, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 2, 2, 3, 3, 2, 3, 3, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
OFFSET
1,1
COMMENTS
The ratio is an integer for n = 1, 2, 3, 11, 43, 53, ...
LINKS
FORMULA
a(n) = floor(A001358(n)/n).
EXAMPLE
a(1) = floor(4/1) = 4 because 4 is the first semiprime.
a(2) = floor(6/2) = 3 because 6 is the second semiprime.
a(3) = floor(9/3) = 3 because 9 is the third semiprime.
a(4) = floor(10/4) = 2 because 4 is the fourth semiprime.
MATHEMATICA
sp=Select[Range[290], PrimeOmega[#]==2&]; l=Length[sp]; Table[Floor[sp[[n]]/n], {n, l}] (* James C. McMahon, Oct 11 2024 *)
PROG
(PARI) seq(n)={my(a=vector(n), k=1, i=0); while(k<=#a, i++; if(bigomega(i)==2, a[k]=i\k; k++)); a} \\ Andrew Howroyd, Nov 08 2019
CROSSREFS
Cf. A001358.
Sequence in context: A327869 A196274 A073871 * A241180 A117323 A016502
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Aug 18 2006
EXTENSIONS
Terms a(61) and beyond from Andrew Howroyd, Nov 08 2019
STATUS
approved