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A168117
Primes whose indices are perfect numbers.
0
13, 107, 3541, 83243, 645072299, 215186133599, 3839719253921
OFFSET
1,1
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
Sequence in context: A164301 A322499 A087305 * A244176 A038384 A038385
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