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 A181174 #8 Jun 02 2025 03:12:53
%S A181174 1,2,24,320,11264,688128,90177536,22817013760,11751030521856,
%T A181174 11997870882291712,24607668363952390144,100719222642454151823360,
%U A181174 825394103341888069030641664,13520781109074923362448234774528
%N A181174 The "Row2" sums of the powers-of-2 triangle A000079.
%C A181174 The a(n) represent the "Row2" sums, see A180662, of the powers-of-2 triangle A000079. This sequence is related to the Jacobsthal and triangular numbers.
%F A181174 a(n) = 2^(n*(n+1)/2)*(2^(n+1)+(-1)^n)/3.
%F A181174 a(n) = A001045(n+1)*2^A000217(n).
%t A181174 f[k_] := (2^k) (-1)^(k + 1)
%t A181174 t[n_] := Table[f[k], {k, 1, n}]
%t A181174 a[n_] := SymmetricPolynomial[n - 1, t[n]]
%t A181174 Table[a[n], {n, 1, 22}] (* A181174 signed *)
%t A181174 (* _Clark Kimberling_, Dec 30 2011 *)
%K A181174 easy,nonn
%O A181174 0,2
%A A181174 _Johannes W. Meijer_, Oct 10 2010