This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A152923 #11 Oct 17 2024 12:03:27 %S A152923 1,4,64,1024,4194304,1073741824,17179869184,288230376151711744, %T A152923 332306998946228968225951765070086144, %U A152923 23945242826029513411849172299223580994042798784118784,1645504557321206042154969182557350504982735865633579863348609024 %N A152923 a(n) = 2^(2*p-1)/8, where p is A000043(n). %C A152923 Ultraperfect numbers (A139306), divided by 8. %H A152923 Amiram Eldar, <a href="/A152923/b152923.txt">Table of n, a(n) for n = 1..15</a> %F A152923 a(n) = A139306(n)/8 = A152921(n)/4 = A152922(n)/2. %t A152923 2^(2 * MersennePrimeExponent[Range[10]] - 4) (* _Amiram Eldar_, Oct 17 2024 *) %Y A152923 Cf. A000043, A139292, A139306, A152921, A152922. %K A152923 nonn %O A152923 1,2 %A A152923 _Omar E. Pol_, Dec 15 2008 %E A152923 a(9)-a(11) from _Amiram Eldar_, Oct 17 2024