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!)
A330824 Numbers of the form 2^(2*p), where p is a Mersenne exponent, A000043. 4
16, 64, 1024, 16384, 67108864, 17179869184, 274877906944, 4611686018427387904, 5316911983139663491615228241121378304 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also the second element of the power-spectral basis of A064591. The first element of the power-spectral basis of A064591 is A133049.

LINKS

Table of n, a(n) for n=1..9.

FORMULA

a(n) = 2^(2*A000043(n)) = 4^A000043(n).

EXAMPLE

a(1) = 2^(2*2) = 16. Also A133049(1) = 3^2 = 9, and the spectral basis of A064591(1) = 24 is {9, 16}, consisting of primes and powers.

MAPLE

a := proc(n) if isprime(2^n-1) then return 2^(2*n) fi; end;

[seq(a(n), n=1..31)]; # ithprime(31) = 127

PROG

(PARI) forprime(p=1, 99, isprime(2^p-1)&&print1(4^p", ")) \\ or better: {A330824(n)=4^A000043(n)}. - M. F. Hasler, Feb 07 2020

CROSSREFS

Cf. A000043, A000668, A064591, A132794, A133049.

Sequence in context: A255576 A065404 A327496 * A189806 A222748 A283271

Adjacent sequences:  A330821 A330822 A330823 * A330825 A330826 A330827

KEYWORD

nonn

AUTHOR

Walter Kehowski, Jan 06 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 August 13 22:34 EDT 2020. Contains 336465 sequences. (Running on oeis4.)