A152922 a(n) = 2^(2*p-1)/4, where p is A000043(n).

2, 8, 128, 2048, 8388608, 2147483648, 34359738368, 576460752303423488, 664613997892457936451903530140172288, 47890485652059026823698344598447161988085597568237568

Offset: 1

Author

Omar E. Pol, Dec 15 2008

Keywords

• nonn

Comments

Ultraperfect numbers (A139306), divided by 4.

Links

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

Crossrefs

Cf. A000043, A139290, A139306, A152921, A152923.

Programs

Mathematica

2^(2 * MersennePrimeExponent[Range[10]] - 3) (* Amiram Eldar, Oct 17 2024 *)

Formula

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

Extensions

a(9)-a(10) from Amiram Eldar, Oct 17 2024