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A192394
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Number of semiprimes in the range (prime(n), prime(n)+sqrt(prime(n))).
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1
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0, 1, 1, 1, 1, 2, 1, 2, 2, 2, 3, 2, 1, 2, 2, 3, 2, 2, 2, 2, 2, 4, 4, 4, 1, 2, 2, 2, 4, 6, 3, 4, 5, 5, 4, 4, 5, 2, 3, 4, 3, 4, 4, 6, 6, 7, 7, 3, 2, 2, 3, 4, 4, 5, 4, 4, 2, 3, 4, 4, 6, 8, 5, 6, 7, 7, 5, 4, 5, 5, 6, 5, 5, 5, 8
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OFFSET
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1,6
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LINKS
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EXAMPLE
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a(1)=0 because there are no semiprimes in the range (2, 2+sqrt(2));
a(2)=1 because there is one semiprime (4) in the range (3, 3+sqrt(3)).
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MAPLE
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A192394 := proc(n) local a, p, s; a := 0 ; p := ithprime(n) ; for s from p to floor( p+sqrt(p)) do if isA001358(s) then a := a+1 ; end if; end do: a; end proc: # R. J. Mathar, Jul 01 2011
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MATHEMATICA
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(* First run A072000 to define semiPrimePi *) Table[semiPrimePi[Prime[n] + Sqrt[Prime[n]]] - semiPrimePi[Prime[n]], {n, 75}] (* Alonso del Arte, Jul 01 2011 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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