A257535 Decimal expansion of the imaginary part of -E_1(i), i being the imaginary unit.

6, 2, 4, 7, 1, 3, 2, 5, 6, 4, 2, 7, 7, 1, 3, 6, 0, 4, 2, 8, 9, 9, 6, 8, 3, 7, 7, 8, 1, 6, 5, 7, 1, 7, 8, 4, 2, 8, 6, 2, 4, 6, 7, 4, 4, 9, 4, 9, 4, 4, 1, 1, 2, 0, 0, 1, 6, 0, 1, 7, 5, 2, 2, 5, 8, 7, 2, 2, 1, 1, 6, 6, 6, 0, 2, 3, 0, 6, 5, 8, 1, 2, 2, 5, 3, 1, 5, 2, 7, 9, 5, 8, 9, 3, 1, 7, 8, 2, 2, 7, 7, 6, 0, 5, 0

Offset

0,1

Comments

E_1(z) = Integral_{t>=1}(exp(-t*z)/t) is the exponential integral.

Links

Stanislav Sykora, Table of n, a(n) for n = 0..2000

Wikipedia, Exponential integral.

Formula

Equals imag(E_1(-i)).

Equals (Pi/2) - A099281.

Example

0.6247132564277136042899683778165717842862467449494411200160175...

Mathematica

RealDigits[Pi/2 - SinIntegral[1], 10, 105][[1]] (* Amiram Eldar, May 24 2023 *)

Prog

(PARI) a = imag(-eint1(I))

Crossrefs

Cf. A099281, A099282, A099285.

Sequence in context: A061496 A125115 A202244 * A020831 A298777 A156590

Adjacent sequences: A257532 A257533 A257534 * A257536 A257537 A257538

Keyword

nonn,cons

Author

Stanislav Sykora, Apr 28 2015

Status

approved