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 A249058 a(n) = number of primes less than the square root of the (2^n)-th prime 2
 0, 0, 1, 2, 4, 5, 7, 9, 12, 17, 24, 32, 45, 61, 82, 114, 154, 215, 293, 404, 557, 766, 1057, 1459, 2025, 2800, 3880, 5379, 7470, 10368, 14414, 20030, 27864, 38745, 53982, 75206, 104799, 146151, 203821, 284381, 396976, 554303, 774256, 1081749, 1511871, 2113506 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Jens Kruse Andersen, Table of n, a(n) for n = 0..56 FORMULA a(n) = primepi(sqrt(A033844(n))). - Jens Kruse Andersen, Oct 20 2014 MATHEMATICA PrimePi[Sqrt[Prime[2^n]]] CROSSREFS Cf. A033844. Related to analysis of A247665. Sequence in context: A069355 A212661 A288511 * A105771 A193494 A161832 Adjacent sequences:  A249055 A249056 A249057 * A249059 A249060 A249061 KEYWORD nonn AUTHOR Russ Cox, Oct 19 2014 EXTENSIONS More terms from Jens Kruse Andersen, Oct 20 2014 STATUS approved

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Last modified January 22 14:02 EST 2020. Contains 331149 sequences. (Running on oeis4.)