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 A272177 #10 Aug 29 2024 18:32:16
%S A272177 1,1,2,6,42,162,634,2726,9330,37814,186034,623934,2370354,10505738,
%T A272177 37417658,113248562,738713250,2753640290,7522970666,46292418830,
%U A272177 146514514914,496491671978,2915741154442,9464309679414,39098814277474,173211426442282,652232674100690
%N A272177 Alternating row sum of row 2n in A238453.
%C A272177 The alternating row sums of odd rows in A238453 are 0.
%H A272177 Tom Edgar, <a href="http://www.emis.de/journals/INTEGERS/papers/o62/o62.Abstract.html">Totienomial Coefficients</a>, INTEGERS, 14 (2014), #A62.
%F A272177 a(n) = Sum_{k=0..2n}(-1)^k*A238453(2n,k).
%o A272177 (Sage)
%o A272177 P=[euler_phi(i) for i in [0..100]]
%o A272177 Tr=[[prod(P[1:n+1])/(prod(P[1:k+1])*prod(P[1:(n-k)+1])) for k in [0..n]] for n in [0..len(P)-1]]
%o A272177 L=[sum((-1)^i*x[i] for i in [0..len(x)-1]) for x in Tr]
%o A272177 print([y for y in L if y!=0])
%Y A272177 Cf. A000010, A238453, A272079.
%K A272177 nonn
%O A272177 0,3
%A A272177 _Tom Edgar_, Apr 21 2016