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 A195907 Decimal expansion of Sum_{n = -oo..oo} exp(-n^2). 3
 1, 7, 7, 2, 6, 3, 7, 2, 0, 4, 8, 2, 6, 6, 5, 2, 1, 5, 3, 0, 3, 1, 2, 5, 0, 5, 5, 1, 1, 5, 7, 8, 5, 8, 4, 8, 1, 3, 4, 3, 3, 8, 6, 0, 4, 5, 3, 7, 2, 2, 4, 6, 0, 5, 3, 8, 3, 1, 5, 9, 0, 5, 1, 0, 8, 7, 9, 9, 6, 8, 6, 8, 0, 8, 3, 9, 6, 3, 4, 0, 1, 2, 5, 4, 0, 3, 3, 8, 7, 1, 7, 4, 2, 4, 9, 6, 0, 0, 2, 9, 6, 4, 0, 5, 1, 9, 0, 7, 1, 3, 4, 7, 3, 5, 1 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A Riemann sum approximation to Integral_{-oo..oo} exp(-x^2) dx = sqrt(Pi). REFERENCES Mentioned by N. D. Elkies in a lecture on the Poisson summation formula in Nashville TN in May 2010. LINKS G. C. Greubel, Table of n, a(n) for n = 1..5000 EXAMPLE 1.77263720482665215303125055115785848134338604537224605383159051... For comparison, sqrt(Pi) = 1.7724538509055160272981674833411451827975494561223871282138... (A002161). MATHEMATICA N[Sum[Exp[-n^2], {n, -Infinity, Infinity}], 200] RealDigits[ N[ EllipticTheta[3, 0, 1/E], 115]][[1]] (* Jean-François Alcover, Nov 08 2012 *) PROG (PARI) 1 + 2*suminf(n=1, exp(-n^2)) \\ Charles R Greathouse IV, Jun 06 2016 CROSSREFS Cf. A002161, A218792. Sequence in context: A255272 A303658 A169812 * A126584 A318302 A266271 Adjacent sequences:  A195904 A195905 A195906 * A195908 A195909 A195910 KEYWORD nonn,cons AUTHOR N. J. A. Sloane, Sep 25 2011 STATUS approved

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Last modified October 21 12:12 EDT 2019. Contains 328299 sequences. (Running on oeis4.)