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 A086693 Number of primes less than prime(n)^prime(n). 0
 2, 9, 445, 65685, 11262113374, 9373678643933, 17547676024364306476, 36020106660104388871845 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA a(n) = A064151(prime(n)) = A000720(A051674(n)). - Michel Marcus, Mar 17 2015 EXAMPLE There are 9 primes less than 3^3 = 27, namely 2,3,5,7,11,13,17,19,23. Since 3 is prime(2), a(2) = 9. MATHEMATICA f[n_] := Block[{p = Prime@ n}, PrimePi[p^p]]; Array[f, 5] (* Michael De Vlieger, Mar 17 2015 *) PROG (PARI) primeslesspp(n) = /* primes less than p^p */ { forprime(x=2, n, y=primepi(x^x); print1(y", "); ); } (MAGMA) [ #PrimesUpTo(NthPrime(n)^NthPrime(n)): n in [1..4] ]; // Vincenzo Librandi, Mar 17 2015 CROSSREFS Cf. A064151. Sequence in context: A024225 A266289 A000883 * A085605 A180936 A036878 Adjacent sequences:  A086690 A086691 A086692 * A086694 A086695 A086696 KEYWORD hard,more,nonn AUTHOR Cino Hilliard, Jul 28 2003 EXTENSIONS a(5)-a(7) from David Baugh, Mar 17 2015 a(8) from Chai Wah Wu, Apr 18 2018 STATUS approved

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Last modified February 16 08:26 EST 2019. Contains 320159 sequences. (Running on oeis4.)