cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A386715 Decimal expansion of Integral_{x=0..1} {1/x}^2 * x^2 dx, where {} denotes fractional part.

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Jul 31 2025

Keywords

Examples

			0.05100300999739309270928222394750827333868793548423...
		

References

  • Ovidiu Furdui, Limits, Series, and Fractional Part Integrals: Problems in Mathematical Analysis, New York: Springer, 2013. See section 2.21, pages 103 and 110.

Crossrefs

Cf. A354238 (m=1), this constant (m=2), A386716 (m=3).

Programs

  • Mathematica
    RealDigits[1 - (Zeta[2] + Zeta[3])/3, 10, 120, -1][[1]]
  • PARI
    1 - (zeta(2) + zeta(3))/3

Formula

Equals 1 - (zeta(2) + zeta(3))/3.
Equals 1 - A347213 / 3.
Equals Integral_{x=0..1} Integral_{y=0..1} {x/y}^2 * {y/x}^2 dx dy.
In general, for m >= 1, Integral_{x=0..1} {1/x}^m * x^m dx = Integral_{x=0..1} Integral_{y=0..1} {x/y}^m * {y/x}^m dx dy = 1 - Sum_{k=2..m+1} zeta(k)/(m+1).
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