A281682 Decimal expansion of Sum_{n>=2} 1/A000166(n).

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

Offset

1,2

Links

Table of n, a(n) for n=1..113.

Wikipedia, Subfactorial/Derangement definition

Formula

Equals Sum_{n>=2} 1/round(n!/e).

Example

1.63822707450537064754289311415112266106359324964443616472326282872630582...

Mathematica

a[n_]:=If[n>0, Round[n!/E], 1]; RealDigits[Sum[1/a[n], {n, 2, 500}], 10, 113][[1]](* Indranil Ghosh, Mar 12 2017 *)

Prog

(Derive 6)
PrecisionDigits ≔ 1000
NotationDigits ≔ 1000
sum(1/ROUND(n!/e), n, 2, 500)

Crossrefs

Cf. A000166.

Sequence in context: A115287 A061533 A317969 * A157294 A021098 A307110

Adjacent sequences: A281679 A281680 A281681 * A281683 A281684 A281685

Keyword

nonn,cons

Author

Miguel Alejandro Moreno Barrientos, Jan 26 2017

Status

approved