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A276474 a(n) = ((sqrt(2); sqrt(2))_n + (-sqrt(2); -sqrt(2))_n)/2, where (q; q)_n is the q-Pochhammer symbol.

%I A276474 #27 Feb 16 2025 08:33:36
%S A276474 1,1,-1,-5,15,87,-609,-8337,125055,2695455,-83559105,-4212669825,
%T A276474 265398198975,22347926076735,-2838186611745345,-560679228377509185,
%U A276474 142973203236264842175,47858338570309251530175,-24455611009428027531919425,-19225279650279123532147010625
%N A276474 a(n) = ((sqrt(2); sqrt(2))_n + (-sqrt(2); -sqrt(2))_n)/2, where (q; q)_n is the q-Pochhammer symbol.
%C A276474 The q-Pochhammer symbol (q; q)_n = Product_{k=1..n} (1 - q^k).
%H A276474 G. C. Greubel, <a href="/A276474/b276474.txt">Table of n, a(n) for n = 0..114</a>
%H A276474 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/q-PochhammerSymbol.html">q-Pochhammer Symbol</a>.
%F A276474 (sqrt(2); sqrt(2))_n = a(n) + A276475(n)*sqrt(2).
%F A276474 (-sqrt(2); -sqrt(2))_n = a(n) - A276475(n)*sqrt(2).
%t A276474 Round@Table[(QPochhammer[Sqrt[2], Sqrt[2], n] + QPochhammer[-Sqrt[2], -Sqrt[2], n])/2, {n, 0, 20}]
%Y A276474 Cf. A276475, A263687, A263688.
%K A276474 sign
%O A276474 0,4
%A A276474 _Vladimir Reshetnikov_, Sep 12 2016