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 A067871 Number of primes between consecutive prime powers. 2
 2, 0, 2, 3, 0, 2, 4, 3, 4, 8, 0, 1, 8, 14, 1, 7, 7, 4, 25, 2, 15, 15, 17, 16, 10, 45, 2, 44, 20, 26, 18, 0, 2, 28, 52, 36, 42, 32, 45, 45, 47, 19, 30, 106, 36, 35, 4, 114, 28, 135, 89, 42, 87, 42, 34, 66, 192, 106, 56, 23, 39, 37, 165, 49, 37, 262, 58, 160, 22 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Lei Zhou, Table of n, a(n) for n = 1..667 FORMULA a(n) = A000720(A025475(n+3)) - A000720(A025475(n+2)) - David Wasserman, Dec 20 2002 EXAMPLE The first few prime powers are 4, 8, 9, 16. The first few primes are 2, 3, 5, 7, 11, 13. We have (4), 5, 7, (8), (9), 11, 13, (16) and so the sequence begins with 2, 0, 2. MATHEMATICA t = {}; cnt = 0; Do[If[PrimePowerQ[n], If[FactorInteger[n][[1, 2]] == 1, cnt++, AppendTo[t, cnt]; cnt = 0]], {n, 4 + 1, 30000}]; t (* T. D. Noe, May 21 2013 *) CROSSREFS Sequence in context: A127710 A137510 A247303 * A198632 A060155 A209127 Adjacent sequences:  A067868 A067869 A067870 * A067872 A067873 A067874 KEYWORD nonn,easy AUTHOR Jon Perry, Mar 07 2002 EXTENSIONS More terms from David Wasserman, Dec 20 2002 STATUS approved

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Last modified September 16 02:16 EDT 2019. Contains 327088 sequences. (Running on oeis4.)