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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A063917 Smallest k such that k!!! is a multiple of n. 3
1, 2, 3, 4, 5, 6, 7, 8, 6, 5, 11, 12, 13, 7, 15, 8, 17, 6, 19, 8, 21, 11, 23, 12, 20, 13, 9, 7, 29, 15, 31, 14, 33, 17, 10, 12, 37, 19, 39, 8, 41, 21, 43, 11, 15, 23, 47, 18, 28, 20, 51, 13, 53, 9, 11, 10, 57, 29, 59, 15, 61, 31, 21, 16, 13, 33, 67, 17, 69 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

F. Smarandache, "Some problems in number theory", Student Conference, University of Craiova, Department of Mathematics, 1979.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..2000

Anonymous, Smarandache k-factorial

EXAMPLE

a(16) = 8 because 8!!! = 8*(8 - 3)*(8 - 6) = 8*5*2 which is divisible by 16 and 8 is the smallest integer with this property.

MATHEMATICA

f[n_] := Product[k, {k, n, 1, -3}]; a[n_] := Module[{k = 1}, While[! Divisible[ f[k], n], k++]; k]; Array[a, 100]  (* Amiram Eldar, Dec 08 2018 *)

With[{tbl=Table[Times@@Range[k, 1, -3], {k, 100}]}, Table[Position[tbl, _?(Divisible[ #, n]&), 1, 1], {n, 70}]]//Flatten (* Harvey P. Dale, Feb 11 2020 *)

CROSSREFS

Cf. A007661.

Sequence in context: A245354 A097377 A234741 * A234344 A331298 A325351

Adjacent sequences:  A063914 A063915 A063916 * A063918 A063919 A063920

KEYWORD

nonn

AUTHOR

Mike Antholy (mikeantholy(AT)yahoo.ca), Aug 31 2001

EXTENSIONS

Offset changed and more terms by Amiram Eldar, Dec 08 2018

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 June 18 06:02 EDT 2021. Contains 345098 sequences. (Running on oeis4.)