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!)
A056743 a(n) = phi(2^prime(n) - 1)/prime(n); a(0) = 0 by convention. 2
0, 1, 2, 6, 18, 176, 630, 7710, 27594, 356960, 18407808, 69273666, 3697909056, 53630700752, 204064589160, 2992477516800, 169917983040000, 9770466930024800, 37800705069076950, 2202596295934991760 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..19.

MAPLE

with numtheory; A056743 := proc(n) phi( 2^ithprime(n) - 1 )/ithprime(n); end;

MATHEMATICA

Phi( A001348) / A000040. Table[EulerPhi[(2^Prime[n] - 1)]/Prime[n], {n, 1, 25}]

CROSSREFS

Cf. A000020, A064535.

Sequence in context: A212653 A323104 A208456 * A064535 A240643 A262971

Adjacent sequences:  A056740 A056741 A056742 * A056744 A056745 A056746

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Aug 14 2000

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 September 17 14:07 EDT 2021. Contains 347478 sequences. (Running on oeis4.)