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 A153804 #15 Oct 21 2024 04:36:23
%S A153804 0,0,0,0,1,2,1,6,19,30,38,45,240,282,616,1075,1111,1578,2093,2176,
%T A153804 4808,4931,5565,9924,10802,11554,22197,43068,55197,65968,107982,
%U A153804 378354,429648,628824,699060,1488035,1510610,3486215,6733375,10497919,12018202,12982385,15201133
%N A153804 a(n) = A153801(n)/2.
%H A153804 Amiram Eldar, <a href="/A153804/b153804.txt">Table of n, a(n) for n = 1..48</a>
%F A153804 a(n) = (A000043(n) - A000040(n))/2.
%t A153804 With[{max = 48}, (MersennePrimeExponent[Range[max]] - Prime[Range[max]]) / 2] (* _Amiram Eldar_, Oct 21 2024 *)
%Y A153804 Cf. A000040, A000043, A153800, A153801, A153802.
%K A153804 nonn
%O A153804 1,6
%A A153804 _Omar E. Pol_, Jan 13 2009
%E A153804 More terms from _R. J. Mathar_, Mar 14 2009
%E A153804 More terms from _Jinyuan Wang_, Mar 02 2020