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The sum of the volumes of an infinite number of unit $n$-spheres each increasing in dimension is given by $$V_{\infty}= \sum_{n=0}^{\infty} V(n)$$ which gives us $$\sum_{n=0}^{\infty}\frac{\pi^{\frac{n}{2}}}{\Gamma(\frac{n}{2}+1)} = 46 \, \,(- 0.00067...)$$ which is surprisingly close to an integer. Its closed form can be written as $$V_{\infty} = e^{\pi}(\text{erf}(\sqrt{\pi})+1)$$

For the surface area equivalent, its closed form is $$S_{\infty} = 2\pi V_{\infty}+2$$ $$= 289 \, \,(+ 0.22289...)$$ For $S_{\infty}$, though it has a nice closed form, I wouldn't consider it being 'strangely' close to an integer. However I wonder why $V_{\infty}$ is so close to an integer value from a philosophical point of view as well as mathematical. It also seems like its closed form is weirdly 'nice' containing $e^{\pi}$ and $\sqrt{\pi}$ as argument of the error function, so for that to be this close to an integer could perhaps mean it is less likely to be a coincidence but this reasoning isn't mathematical so it doesn't really matter how 'nice' the closed form is. I'm curious, and look forward to know what you guys think


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Mako
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    Sometimes nice near-integer explanations exist, but with this particular problem I don't know of one or expect one to be known. – J.G. Dec 13 '23 at 13:10
  • I'm not sure whether to expect one or not- but it seems so wild and coincidental to me – Mako Dec 13 '23 at 13:16
  • "from a philosophical point of view" - what does philosophy has to do with anything here? – Yuriy S Dec 13 '23 at 13:47
  • @YuriyS The infinite addition of volumes of ever increasing dimensional spheres being so close to an integer, could be interesting from a philosophical stand-point. Of course this depends on whether there is a nice explanation, or if this were just coincidence. If it weren't a coincidence then philosophy is relevent – Mako Dec 13 '23 at 13:53
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    Looks like a simple coincidence to me. – K.defaoite Dec 15 '23 at 20:20
  • Remember our notion of closeness is subjective and quite arbitrary. – FShrike Dec 15 '23 at 22:39
  • @FShrike But look at Heegner numbers. Very very close to integers and it actually means something. This is less close to an integer than Heegner numbers are sure, but it might still have an interesting explanation – Mako Dec 15 '23 at 22:41
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    Wait a second: https://math.stackexchange.com/questions/1080868/is-the-almost-identity-sum-k-0-infty-left-pi-frac-k2-big-gamma-lef?rq=1 this was asked almost 10 years ago – FShrike Dec 15 '23 at 22:45
  • @FShrike This is interesting! Thanks alot – Mako Dec 15 '23 at 22:51
  • What do you mean by "why"? I don't think mathematics has a notion of "why". Mathematical theorems just are, there is no reason behind them. At least, that is what I think. You have to define "why" rigorously if you want a good answer. – user107952 Dec 15 '23 at 23:06
  • @user107952 I know, which is why this isn't exactly a mathematical question, but if someone can put a "why" to it that's what I'm looking for – Mako Dec 15 '23 at 23:12
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    I agree that is unlikely that this coincidence will generate a particularly satisfying why. I disagree with this slander that mathematics is incapable of answering a why question. I think many proofs could be given in response to a why question. Why does pi appear in Leibniz formula? Why do sine curves model the behavior of springs so accurately? Why might not be a precise mathematical question. But it doesn't seem like the wrong word. Imho – Mason Dec 16 '23 at 00:44

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