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!)
A338364 a(n) = Product_{k=1..n} phi(prime(k)-1). 1
1, 1, 1, 2, 4, 16, 64, 512, 3072, 30720, 368640, 2949120, 35389440, 566231040, 6794772480, 149484994560, 3587639869440, 100453916344320, 1607262661509120, 32145253230182400, 771486077524377600, 18515665860585062400, 444375980654041497600, 17775039226161659904000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..23.

EXAMPLE

a(5) = phi(1)*phi(2)*phi(4)*phi(6)*phi(10) = 1*1*2*2*4 = 16.

MAPLE

with(NumberTheory);

f:=n->mul(phi(ithprime(k)-1), k=1..n);

[seq(f(n), n=1..32)];

PROG

(PARI) a(n) = prod(k=1, n, eulerphi(prime(k)-1)); \\ Michel Marcus, Nov 04 2020

CROSSREFS

Cf. A000010, A008330, A002110.

Sequence in context: A153998 A154001 A154004 * A060656 A271234 A061286

Adjacent sequences:  A338361 A338362 A338363 * A338365 A338366 A338367

KEYWORD

nonn

AUTHOR

Marc LeBrun and N. J. A. Sloane, Nov 04 2020

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 April 10 21:34 EDT 2021. Contains 342856 sequences. (Running on oeis4.)