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 A023836 #17 Jun 13 2025 07:45:33
%S A023836 0,3,4,6,6,8,8,11,11,12,11,14,13,16,13,17,14,18,15,19,20,21,21,23,23,
%T A023836 22,22,24,22,27,22,29,26,28,27,31,29,31,31,31,31,32,32,35,34,35,32,39,
%U A023836 34,37,35,38,37,40,37,41,40,42,40,43,43,44,43,46,43,45,42,46,45,48,43,50,46,48,50,50,50
%N A023836 Sum of exponents in prime-power factorization of C(4n,2n-2).
%H A023836 Ivan Neretin, <a href="/A023836/b023836.txt">Table of n, a(n) for n = 1..10000</a>
%F A023836 From _Amiram Eldar_, Jun 13 2025: (Start)
%F A023836 a(n) = A023817(2*n).
%F A023836 a(n) = A023835(n) - A001222(2*n+2) + A001222(2*n-1). (End)
%t A023836 Join[{0},Rest[Total[Last[Transpose[FactorInteger[#]]]]&/@(Binomial[ 4#,2#-2]&/@Range[80])]] (* _Harvey P. Dale_, Jun 07 2011 *)
%t A023836 a[n_] := PrimeOmega[Binomial[4*n, 2*n-2]]; Array[a, 100] (* _Amiram Eldar_, Jun 13 2025 *)
%o A023836 (PARI) a(n) = bigomega(binomial(4*n,2*n-2)); \\ _Amiram Eldar_, Jun 13 2025
%Y A023836 Cf. A001222, A023817, A023826, A023827, A023828, A023829, A023830, A023831, A023832, A023834, A023835.
%K A023836 nonn
%O A023836 1,2
%A A023836 _Clark Kimberling_