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A162567
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Primes p such that pi(p) divides p-1 and/or p+1, where pi(p) is the number of primes <= p.
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0
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2, 3, 5, 7, 11, 13, 29, 37, 43, 349, 359, 1087, 1091, 3079, 8423, 64579, 64591, 64601, 64609, 64661, 64709, 481043, 481067, 1304707, 3523969, 3524249, 3524317, 3524387, 9558541, 9559799, 9560009, 9560039, 25874767, 70115921, 189962009
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| The 10th prime is 29. Since 10 divides 29+1 = 30, then 29 is in the sequence. The 12th prime is 37. Since 12 divides 37-1=36, then 37 is in the sequence.
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MAPLE
| isA162567 := proc(p) RETURN ( (p-1) mod numtheory[pi](p) = 0 or (p+1) mod numtheory[pi](p) = 0 ) ; end: for n from 1 to 50000 do p := ithprime(n) ; if isA162567(p) then printf("%d, ", p) ; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 30 2009] - a(10)-a(35) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jul 29 2009
with(numtheory): a := proc (n) if `mod`(ithprime(n)-1, pi(ithprime(n))) = 0 or `mod`(ithprime(n)+1, pi(ithprime(n))) = 0 then ithprime(n) else end if end proc: seq(a(n), n = 1 .. 250000); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 31 2009] - a(10)-a(35) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jul 29 2009
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CROSSREFS
| Sequence in context: A111252 A181525 A082843 * A067908 A187614 A191077
Adjacent sequences: A162564 A162565 A162566 * A162568 A162569 A162570
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet, Jul 06 2009
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EXTENSIONS
| a(10)-a(35) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jul 29 2009
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