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

0,1

Comments

This constant has an interesting simple continued fraction representation.

359/720 approximates this constant to 19 significant digits.

Links

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

Example

0.498611111111111111127228486822072294...

Mathematica

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

Prog

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

Crossrefs

Cf. A386384 (continued fraction expansion).

Cf. A363842, A336810.

Sequence in context: A385555 A370565 A370567 * A371500 A197580 A081382

Adjacent sequences: A387265 A387266 A387267 * A387269 A387270 A387271

Keyword

nonn,cons

Author

Daniel Hoyt, Aug 24 2025

Extensions

a(999) in the b-file was rounded up; corrected by Georg Fischer, Mar 02 2026

Status

approved