login
The OEIS is supported by the many generous donors to the OEIS 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 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A118333 Largest prime factor of n!! + (n+1)!!. 2
2, 3, 5, 11, 23, 7, 17, 163, 443, 29, 73, 251, 4027, 2477, 499, 199, 883, 47, 2671, 308333, 2099, 859, 510481, 10429, 514519, 29629, 51713, 42337, 5407, 13841, 151733, 2448023843, 3133033, 89101, 61613, 19448653009, 50136277, 63259211 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

First five terms coincide with A118332 because n!! + (n+1)!! is prime for n = 0, 1, 2, 3, 4. At n>4, n!! + (n+1)!! is always composite.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..100

MATHEMATICA

Table[FactorInteger[n!!+(n+1)!! ][[ -1, 1]], {n, 0, 40}]

FactorInteger[#][[-1, 1]]&/@(Total/@Partition[Range[0, 40]!!, 2, 1]) (* Harvey P. Dale, Mar 22 2019 *)

CROSSREFS

Cf. A118332.

Sequence in context: A073879 A073880 A118332 * A131101 A188534 A214196

Adjacent sequences: A118330 A118331 A118332 * A118334 A118335 A118336

KEYWORD

nonn

AUTHOR

Zak Seidov, Apr 23 2006

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 4 02:16 EST 2022. Contains 358544 sequences. (Running on oeis4.)