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A242812
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Decimal expansion of the expected number of returns to the origin of a random walk on a 4-d lattice.
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8
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1, 2, 3, 9, 4, 6, 7, 1, 2, 1, 8, 4, 8, 4, 8, 1, 7, 1, 2, 6, 7, 8, 6, 9, 7, 6, 6, 4, 8, 5, 9, 0, 0, 0, 7, 1, 0, 1, 5, 3, 2, 8, 9, 0, 6, 9, 1, 6, 1, 7, 5, 8, 6, 5, 6, 9, 5, 3, 4, 0, 1, 8, 5, 0, 7, 1, 6, 2, 8, 1, 3, 3, 8, 6, 5, 5, 5, 6, 3, 3, 3, 1, 0, 3, 2, 3, 9, 3, 3, 0, 4, 7, 3, 5, 3, 8, 9, 3, 9, 2, 8, 5, 9, 9, 1, 8
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OFFSET
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1,2
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REFERENCES
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Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.9 Polya's random walk constants, p. 323.
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LINKS
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FORMULA
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m(d) = d/(2*Pi)^d*multipleIntegral(-Pi..Pi) (d-sum_(k=1..d) cos(t_k))^(-1) dt_1 dt_2 ... dt_d, where d is the lattice dimension.
m(d) = Integral_(t>0) exp(-t)*BesselI(0,t/d)^d dt where BesselI(0,x) is the zeroth modified Bessel function.
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EXAMPLE
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1.239467121848481712678697664859...
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MAPLE
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m4:= int(exp(-t)*BesselI(0, t/4)^4, t=0..infinity):
s:= convert(evalf(m4, 120), string):
map(parse, subs("."=NULL, [seq(i, i=s)]))[]; # Alois P. Heinz, May 23 2014
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MATHEMATICA
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digits = 50; NIntegrate[BesselI[0, t/4]^4*Exp[-t], {t, 0, Infinity}, PrecisionGoal -> digits, WorkingPrecision -> 350] // RealDigits [#, 10, digits]& // First (* after Ryan Propper *)
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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