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A351401
Decimal expansion of erfi(1)/e, where erfi is the imaginary error function.
1
6, 0, 7, 1, 5, 7, 7, 0, 5, 8, 4, 1, 3, 9, 3, 7, 2, 9, 1, 1, 5, 0, 3, 8, 2, 3, 5, 8, 0, 0, 7, 4, 4, 9, 2, 1, 1, 6, 1, 2, 2, 0, 9, 2, 8, 6, 6, 5, 1, 5, 6, 9, 1, 5, 9, 1, 6, 9, 4, 4, 1, 9, 1, 9, 2, 7, 2, 0, 8, 7, 6, 9, 4, 9, 2, 0, 2, 8, 1, 1, 8, 2, 0, 1, 6, 3, 9, 1, 3, 1, 6, 5, 2, 6, 3, 3, 2, 6, 8, 5, 4, 8, 1, 0, 4
OFFSET
0,1
COMMENTS
The alternating sum of reciprocals of the factorials of the positive half-integers.
REFERENCES
Rudolf Gorenflo, Anatoly A. Kilbas, Francesco Mainardi, and Sergei Rogosin, Mittag-Leffler Functions, Related Topics and Applications, New York, NY: Springer, 2020. See p. 94, eq. (4.12.9.6).
Constantin Milici, Gheorghe Drăgănescu, and J. Tenreiro Machado, Fractional Differential Equations, Introduction to Fractional Differential Equations, Springer, Cham, 2019. See p. 12, eq. (1.9).
LINKS
Eric Weisstein's World of Mathematics, Erfi.
Eric Weisstein's World of Mathematics, Mittag-Leffler Function.
FORMULA
Equals Sum_{k>=0} (-1)^k/(k + 1/2)! = Sum_{k>=1} (-1)^(k+1)/Gamma(k + 1/2).
Equals E_{1, 3/2}(-1), where E_{a,b}(z) is the two-parameter Mittag-Leffler function.
Equals (-1/sqrt(Pi)) * Sum_{k>=1) (-2)^k/(2*k-1)!!.
Equals A068985 * A099288.
EXAMPLE
0.60715770584139372911503823580074492116122092866515...
MAPLE
evalf(exp(-1)*erfi(1), 120); # Alois P. Heinz, Feb 10 2022
MATHEMATICA
RealDigits[Erfi[1]/E, 10, 100][[1]]
PROG
(PARI) real(-I*(1.0-erfc(I)))/exp(1) \\ Michel Marcus, Feb 10 2022
KEYWORD
nonn,cons
AUTHOR
Amiram Eldar, Feb 10 2022
STATUS
approved