login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A067911 Product of GCD(k,n) for 1 <= k <= n. 7
1, 2, 3, 8, 5, 72, 7, 128, 81, 800, 11, 41472, 13, 6272, 30375, 32768, 17, 3359232, 19, 20480000, 750141, 247808, 23, 13759414272, 15625, 1384448, 1594323, 5035261952, 29, 30233088000000, 31, 2147483648, 235782657, 37879808 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

T. D. Noe, Table of n, a(n) for n=1..500

L. Toth, A survey of gcd-sum functions, J. Int. Seq. 13 (2010) # 10.8.1

FORMULA

a(n) = Product_{ d divides n } d^phi(n/d). - Vladeta Jovovic, Mar 08 2004

a(n) = n*A051190(n). - Peter Luschny, Apr 07 2013

MAPLE

with(numtheory): a := n -> mul(d^phi(n/d), d = divisors(n)):

seq(a(i), i = 1..34); # Peter Luschny, Apr 07 2013

PROG

(Sage)

A067911 = lambda n: mul(gcd(n, i) for i in range(n))

[A067911(n) for n in (1..34)] # Peter Luschny, Apr 07 2013

(PARI) a(n) = prod(k=1, n, gcd(k, n)); \\ Michel Marcus, Aug 23 2016

CROSSREFS

Cf. A051190, A051696.

In A018804 the product is replaced by sum.

Product of terms in n-th row of A050873.

Sequence in context: A112283 A136182 A170911 * A243103 A051696 A066570

Adjacent sequences:  A067908 A067909 A067910 * A067912 A067913 A067914

KEYWORD

nonn

AUTHOR

Sharon Sela (sharonsela(AT)hotmail.com), Mar 10 2002

EXTENSIONS

Extended and edited by John W. Layman, Mar 14 2002

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 22 15:27 EST 2017. Contains 295089 sequences.