A152923 a(n) = 2^(2*p-1)/8, where p is A000043(n).

1, 4, 64, 1024, 4194304, 1073741824, 17179869184, 288230376151711744, 332306998946228968225951765070086144, 23945242826029513411849172299223580994042798784118784, 1645504557321206042154969182557350504982735865633579863348609024

Offset: 1

Author

Omar E. Pol, Dec 15 2008

Keywords

• nonn

Comments

Ultraperfect numbers (A139306), divided by 8.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..15

Crossrefs

Cf. A000043, A139292, A139306, A152921, A152922.

Programs

Mathematica

2^(2 * MersennePrimeExponent[Range[10]] - 4) (* Amiram Eldar, Oct 17 2024 *)

Formula

a(n) = A139306(n)/8 = A152921(n)/4 = A152922(n)/2.

Extensions

a(9)-a(11) from Amiram Eldar, Oct 17 2024