A165144 Number of semiprimes between two primes squared.
1, 5, 7, 22, 15, 33, 23, 49, 88, 35, 114, 79, 48, 100, 148, 189, 57, 201, 139, 78, 230, 158, 269, 370, 192, 102, 215, 112, 211, 803, 259, 390, 150, 666, 147, 430, 471, 317, 485, 506, 152, 869, 168, 364, 184, 1144, 1213, 404, 206, 433, 613, 217, 1134, 702, 720, 712
Offset: 1
Keywords
Programs
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Maple
A165144 := proc(n) a := 0 ; for k from ithprime(n)^2+1 to ithprime(n+1)^2-1 do if numtheory[bigomega](k) = 2 then a := a+1 ; fi ; end do ; a ; end proc: seq(A165144(n),n=1..80) ; # R. J. Mathar, Jan 30 2010
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Mathematica
Table[Count[Range[Prime[p]^2+1,Prime[p+1]^2-1],?(PrimeOmega[#]==2&)],{p,60}] (* _Harvey P. Dale, Oct 05 2024 *)
Formula
a(n) = A217019(n) - 1. - Flávio V. Fernandes, Nov 19 2020
Extensions
a(7) corrected and terms beyond a(7) added by R. J. Mathar, Jan 30 2010