A387399 Decimal expansion of Sum_{k>=0} 1/(2^k)!.

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

Offset

1,2

Comments

This constant has an interesting simple continued fraction expansion.

Links

Daniel Hoyt, Table of n, a(n) for n = 1..3000

Example

1.541691468254016048741577842106942639843...

Mathematica

RealDigits[N[Sum[1/(2^k)!, {k, 0, Infinity}], 120]][[1]] (* Amiram Eldar, Apr 17 2026 *)

Prog

(PARI) suminf(k=0, 1/(2^k)!)

Crossrefs

Cf. A387398 (continued fraction expansion).

Sequence in context: A011503 A296498 A195297 * A336284 A258639 A072222

Adjacent sequences: A387396 A387397 A387398 * A387400 A387401 A387402

Keyword

nonn,cons

Author

Daniel Hoyt, Aug 28 2025

Status

approved