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 A168117 Primes whose indices are perfect numbers. 0
 13, 107, 3541, 83243, 645072299, 215186133599, 3839719253921 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA a(n) = A000040(A000396(n)). EXAMPLE a(1)=13 because the first perfect number is 6 and the 6th prime is 13. a(2)=107 because the second perfect number is 28 and the 28th prime is 107. CROSSREFS Cf. A000040, A000396. Sequence in context: A164301 A322499 A087305 * A244176 A038384 A038385 Adjacent sequences:  A168114 A168115 A168116 * A168118 A168119 A168120 KEYWORD hard,more,nonn AUTHOR Omar E. Pol, Dec 09 2009 EXTENSIONS More terms from Omar E. Pol and Max Alekseyev, Dec 10 2009 STATUS approved

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Last modified December 5 13:26 EST 2019. Contains 329751 sequences. (Running on oeis4.)