login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A248675 Decimal expansion of r = sum_{n >= 0} floor(n/2)!/n!. 4
2, 7, 7, 6, 8, 8, 9, 6, 0, 9, 4, 0, 7, 9, 7, 9, 7, 2, 6, 9, 8, 1, 2, 4, 5, 1, 6, 3, 6, 1, 7, 1, 8, 8, 0, 6, 1, 8, 5, 3, 8, 4, 9, 8, 3, 6, 6, 5, 0, 9, 6, 1, 3, 1, 1, 3, 2, 7, 0, 5, 7, 5, 0, 9, 5, 9, 6, 1, 1, 0, 3, 8, 8, 4, 9, 9, 5, 2, 2, 6, 7, 1, 0, 8, 1, 7 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..1000

FORMULA

r = sum_{n >= 0} p(2,n)*n!/(2*n + 1)!, where p(k,n) is defined at A248664.

EXAMPLE

r = 2.7768896094079797269812451636...

MAPLE

evalf(sum(floor(n/2)!/n!, n=0..infinity), 120); # Vaclav Kotesovec, Oct 17 2014

MATHEMATICA

x = N[Sum[Floor[n/2]!/n!, {n, 0, 200}], 120]

RealDigits[x][[1]]  (* A248675 *)

x = N[Sum[Floor[n/3]!/n!, {n, 0, 200}], 120]

RealDigits[x][[1]]  (* A248676 *)

x = N[Sum[Floor[n/4]!/n!, {n, 0, 200}], 120]

RealDigits[x][[1]]  (* A248677 *)

CROSSREFS

Cf. A248676, A248677, A248664.

Sequence in context: A230160 A063503 A244976 * A068386 A021040 A246553

Adjacent sequences:  A248672 A248673 A248674 * A248676 A248677 A248678

KEYWORD

nonn,easy,cons

AUTHOR

Clark Kimberling, Oct 11 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)