A387268 Decimal expansion of Sum_{k>=0} (-1)^k/(k!)!.

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

Offset: 0

Author

Daniel Hoyt, Aug 24 2025

Keywords

• nonn
• cons
• new

Comments

This constant has an interesting simple continued fraction representation.

359/720 approximates this constant to 19 significant digits.

Examples

			0.498611111111111111127228486822072294...
		

Links

• Daniel Hoyt, Table of n, a(n) for n = 0..999

Crossrefs

Cf. A386384 (continued fraction expansion).

Cf. A363842, A336810.

Programs

Mathematica

RealDigits[Sum[(-1)^k/(k!)!, {k, 0, 6}], 10, 100][[1]]

PARI

suminf(k=0, (-1)^k/(k!)!)