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 A353583 #10 May 08 2022 04:54:54
%S A353583 1,0,1,-1,7,-7,199,-71,484,-368,187909,-610103,2068657,-63614,
%T A353583 1530164189,-1715846683,7628902283,-125125345078,9521826231889,
%U A353583 -17921564328719,291162274608871,-47147385565688,552647133893696333,-36898601487519532,4761064630028162378
%N A353583 Numerators of coefficients c(n) in product expansion of 1 + tan x = Product_{k>=1} 1 + c(k)*x^k.
%C A353583 See A353584 for the denominators, and A353586 for the analog for (tan x)/x.
%H A353583 Giedrius Alkauskas, <a href="http://arxiv.org/abs/0801.0805">One curious proof of Fermat's little theorem</a>, arXiv:0801.0805 [math.NT], 2008.
%H A353583 Giedrius Alkauskas, <a href="https://www.jstor.org/stable/40391097">A curious proof of Fermat's little theorem</a>, Amer. Math. Monthly 116(4) (2009), 362-364.
%H A353583 Giedrius Alkauskas, <a href="https://arxiv.org/abs/1609.09842">Algebraic functions with Fermat property, eigenvalues of transfer operator and Riemann zeros, and other open problems</a>, arXiv:1609.09842 [math.NT], 2016.
%H A353583 H. Gingold, H. W. Gould, and Michael E. Mays, <a href="https://www.researchgate.net/publication/268023169_Power_product_expansions">Power Product Expansions</a>, Utilitas Mathematica 34 (1988), 143-161.
%H A353583 H. Gingold and A. Knopfmacher, <a href="http://dx.doi.org/10.4153/CJM-1995-062-9">Analytic properties of power product expansions</a>, Canad. J. Math. 47 (1995), 1219-1239.
%H A353583 Wolfdieter Lang, <a href="/A157162/a157162.txt">Recurrences for the general problem</a>.
%e A353583 1 + tan x = (1 + x)(1 + 1/3*x^3)(1 - 1/3*x^4/3)(1 + 7/15*x^5)(1 - 7/15*x^5)(...),
%e A353583 and this sequence lists the numerators of (1, 0, 1/3, -1/3, 7/15, -7/15, ...).
%o A353583 (PARI) t=1+tan(x+O(x)^29); vector(#t-1,n,c=polcoef(t,n);t/=1+c*x^n;numerator(c))
%Y A353583 Cf. A353584 (denominators), A353586 / A353587 (similar for (tan x)/x).
%Y A353583 Cf. A170918 / A170919 for a variant.
%K A353583 sign,frac
%O A353583 1,5
%A A353583 _M. F. Hasler_, May 07 2022