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 A272178 #11 Mar 15 2020 05:10:25
%S A272178 1,1,2,10,54,322,1294,4526,20782,93814,371110,1780294,6733918,
%T A272178 22513642,92018398,461754862,1297077342,5790726826,32850248974,
%U A272178 94597335398,454725608974,2080853077822,6173935052878,29922219241486,116844904688830,448338212337298,1975870364475334
%N A272178 Absolute value of alternating row sum of row 2n in A238498.
%C A272178 The alternating row sums of the odd-indexed rows are 0.
%H A272178 Tom Edgar, <a href="http://www.emis.de/journals/INTEGERS/papers/o62/o62.Abstract.html">Totienomial Coefficients</a>, INTEGERS, 14 (2014), #A62.
%F A272178 For n>0, a(n) = Sum_{k=0..2n}(-1)^(k+1)*A238498(2n,k).
%o A272178 (Sage)
%o A272178 P=[0]+[i*prod([(1+1/x) for x in prime_divisors(i)]) for i in [1..100]]
%o A272178 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 A272178 L=[sum((-1)^(i)*x[i] for i in [0..len(x)-1]) for x in Tr]
%o A272178 [abs(y) for y in L if y!=0]
%Y A272178 Cf. A001615, A238498, A272080.
%K A272178 nonn
%O A272178 0,3
%A A272178 _Tom Edgar_, Apr 21 2016