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a(n) = 3^(p-1) + (3^p - 1) where p is the n-th prime.
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%I #8 Aug 26 2015 23:34:13

%S 11,35,323,2915,236195,2125763,172186883,1549681955,125524238435,

%T 91507169819843,823564528378595,600378541187996483,

%U 48630661836227715203,437675956526049436835,35451752478610004383715

%N a(n) = 3^(p-1) + (3^p - 1) where p is the n-th prime.

%e a(1) = 3^(2-1) + 3^2 - 1 = 11.

%t Table[3^(Prime[n] - 1) + (3^Prime[n] - 1), {n, 1, 20}] (* _Stefan Steinerberger_, Feb 28 2006 *)

%Y Cf. A097743.

%K nonn

%O 1,1

%A _Parthasarathy Nambi_, Sep 23 2004

%E More terms from _Stefan Steinerberger_, Feb 28 2006