A139300 - OEIS

%I #8 Jul 10 2025 16:01:38

%S 4,1024,288230376151711744,

%T 1809251394333065553493296640760748560207343510400633813116524750123642650624

%N a(n) = 2^(2p - 1)/8, where p is the n-th Mersenne prime A000668(n).

%F a(n) = 2^(2*A000668(n)-1)/8 = A139294(n)/8.

%t a[n_] := 2^(2^(MersennePrimeExponent[n] + 1) - 6); Array[a, 4] (* _Amiram Eldar_, Jul 10 2025 *)

%Y Cf. A000668, A139294, A139295, A139296, A139297, A139298, A139299, A139301, A139302, A139303, A139304, A139305, A139306.

%K nonn

%O 1,1

%A _Omar E. Pol_, Apr 13 2008

%E a(4) from _Amiram Eldar_, Jul 10 2025