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 A276475 #26 Feb 16 2025 08:33:36
%S A276475 0,-1,1,3,-9,-69,483,5355,-80325,-2081205,64517355,2738408715,
%T A276475 -172519749045,-17158004483445,2179066569397515,365466952872801675,
%U A276475 -93194072982564427125,-36694334101466364023925,18750804725849312016225675
%N A276475 a(n) = ((sqrt(2); sqrt(2))_n - (-sqrt(2); -sqrt(2))_n)/(2*sqrt(2)), where (q; q)_n is the q-Pochhammer symbol.
%C A276475 The q-Pochhammer symbol (q; q)_n = Product_{k=1..n} (1 - q^k).
%H A276475 G. C. Greubel, <a href="/A276475/b276475.txt">Table of n, a(n) for n = 0..114</a>
%H A276475 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/q-PochhammerSymbol.html">q-Pochhammer Symbol</a>.
%F A276475 (sqrt(2); sqrt(2))_n = A276474(n) + a(n)*sqrt(2).
%F A276475 (-sqrt(2); -sqrt(2))_n = A276474(n) - a(n)*sqrt(2).
%t A276475 Round@Table[(QPochhammer[Sqrt[2], Sqrt[2], n] - QPochhammer[-Sqrt[2], -Sqrt[2], n])/(2 Sqrt[2]), {n, 0, 20}]
%Y A276475 Cf. A276474, A263687, A263688.
%K A276475 sign
%O A276475 0,4
%A A276475 _Vladimir Reshetnikov_, Sep 12 2016