Table of n, a(n) for n=1..7.
a(n) = A000040(A000396(n)).
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.
Cf. A000040, A000396.
Sequence in context: A164301 A322499 A087305 * A244176 A038384 A038385
Adjacent sequences: A168114 A168115 A168116 * A168118 A168119 A168120
Omar E. Pol, Dec 09 2009
More terms from Omar E. Pol and Max Alekseyev, Dec 10 2009