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a(n) = 5^prime(n).
8

%I #16 Aug 11 2020 09:52:30

%S 25,125,3125,78125,48828125,1220703125,762939453125,19073486328125,

%T 11920928955078125,186264514923095703125,4656612873077392578125,

%U 72759576141834259033203125,45474735088646411895751953125

%N a(n) = 5^prime(n).

%H Ivan Panchenko, <a href="/A057902/b057902.txt">Table of n, a(n) for n = 1..200</a>

%F a(n) = 5^A000040(n).

%F Sum_{n>=1} 1/a(n) = A132797. - _Amiram Eldar_, Aug 11 2020

%e a(4) = 5^7 = 78125.

%p A057902:=n->5^ithprime(n); seq(A057902(n), n=1..30); # _Wesley Ivan Hurt_, Jun 14 2014

%t 5^Prime@Range@30 (* _Vladimir Joseph Stephan Orlovsky_, Apr 11 2011 *)

%Y Cf. A000040, A034785, A053810, A057902, A132797.

%K nonn

%O 1,1

%A _Henry Bottomley_, Sep 29 2000