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 A173396 #12 Sep 08 2022 08:45:50
%S A173396 2,5,23,51,443,949,4027,8483,142163,296481,1232113,2552405,21095279,
%T A173396 43490633,178977107,367649059,12065310083,24714021721,101124870709,
%U A173396 206667899393,1687804827349,3442891889003,14034579926477,28583749273429
%N A173396 a(n) = A046161(n) + A001803(n).
%H A173396 G. C. Greubel, <a href="/A173396/b173396.txt">Table of n, a(n) for n = 0..1000</a>
%F A173396 a(n) = A101926(n) + A173384(n).
%p A173396 A001803 := proc(n) (2*n+1)*binomial(2*n,n)/4^n ; numer(%) ; end proc:
%p A173396 A046161 := proc(n) binomial(2*n,n)/4^n ; denom(%) ; end proc:
%p A173396 A173386 := proc(n) A001803(n)+A046161(n) ; end proc: # _R. J. Mathar_, Jul 06 2011
%t A173396 Table[Numerator[(2*n+1)*Binomial[2*n, n]/(4^n)] + Denominator[Binomial[2*n, n]/(4^n)], {n,0,30}] (* _G. C. Greubel_, Dec 09 2018 *)
%o A173396 (PARI) for(n=0,30, print1(numerator((2*n+1)*binomial(2*n, n)/(4^n)) + denominator(binomial(2*n, n)/4^n), ", ")) \\ _G. C. Greubel_, Dec 09 2018
%o A173396 (Magma) [Numerator((2*n+1)*Binomial(2*n, n)/(4^n)) + Denominator(Binomial(2*n, n)/(4^n)): n in [0..30]]; // _G. C. Greubel_, Dec 09 2018
%o A173396 (Sage) [(numerator((2*n+1)*binomial(2*n, n)/(4^n)) + denominator(binomial(2*n, n)/(4^n))) for n in range(30)] # _G. C. Greubel_, Dec 09 2018
%o A173396 (GAP) List([0..30], n-> (NumeratorRat((2*n+1)*Binomial(2*n, n)/(4^n)) + DenominatorRat(Binomial(2*n, n)/(4^n)))); # _G. C. Greubel_, Dec 09 2018
%Y A173396 Cf. A173384, A173294, A173296.
%K A173396 nonn
%O A173396 0,1
%A A173396 _Paul Curtz_, Feb 17 2010