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A283743
Decimal expansion of Ei(1)/e, where Ei is the exponential integral function.
2
6, 9, 7, 1, 7, 4, 8, 8, 3, 2, 3, 5, 0, 6, 6, 0, 6, 8, 7, 6, 5, 4, 7, 8, 6, 8, 1, 9, 1, 9, 5, 5, 1, 5, 9, 5, 3, 1, 7, 1, 7, 5, 4, 3, 0, 9, 5, 4, 3, 6, 9, 5, 1, 7, 3, 2, 0, 0, 5, 4, 8, 0, 7, 7, 8, 9, 4, 5, 4, 1, 1, 5, 1, 9, 5, 1, 4, 4, 2, 6, 9, 6, 2, 9, 1, 0, 0, 5, 3, 0, 3, 0, 3, 3, 3, 9, 1, 1, 4, 0, 0, 6
OFFSET
0,1
COMMENTS
Can be considered the value of the divergent series -0! - 1! - 2! - ... ; see Lagarias reference Section 2.5. - Harry Richman, Jun 14 2020.
LINKS
Jeffrey C. Lagarias, Euler's constant: Euler's work and modern developments, arXiv:1303.1856 [math.NT], 2013; Bull. Amer. Math. Soc., 50 (2013), 527-628.
Eric Weisstein's World of Mathematics, Exponential Integral
Eric Weisstein's World of Mathematics, Subfactorial
FORMULA
The real part of subfactorial(-1), that is the real part of Gamma(0,-1)/e.
EXAMPLE
0.6971748832350660687654786819195515953171754309543695173200548...
MATHEMATICA
RealDigits[ExpIntegralEi[1]/E, 10, 102][[1]]
PROG
(PARI) real(-eint1(-1)/exp(1)) \\ Michel Marcus, Jun 15 2020
CROSSREFS
Cf. A000166 (subfactorials), A061382 (Pi/e, the imaginary part of subfactorial(-1)), A091725 (Ei(1)), A073003 (-exp(1)*Ei(-1)).
Sequence in context: A010725 A193594 A011480 * A339764 A229921 A145429
KEYWORD
nonn,cons
AUTHOR
STATUS
approved