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A330819 Numbers of the form M_p^2(M^p+2)^2, where M_p is a Mersenne prime (A000668) and p is a Mersenne exponent (A000043). Also the first element of the spectral basis of A330817. 10
225, 3969, 1046529, 268402689, 4503599493152769, 295147905144993087489, 75557863725364567605249, 21267647932558653957237540927630737409, 28269553036454149273332760011886696242605918383730576346715242738439159809 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The second element of the spectral basis of A330817 is A330820.

LINKS

Walter Kehowski, Table of n, a(n) for n = 1..12

FORMULA

a(n) = A000668(n)^2*(A000668(n)+2)^2.

EXAMPLE

If p=2, then M_2=3, and a(1) = 3^2(3+2)^2 = 15^2 = 225.

MAPLE

A330819:=[]:

for www to 1 do

for i from 1 to 31 do

  #ithprime(31)=127

  p:=ithprime(i);

  q:=2^p-1;

  if isprime(q) then x:=2^(2*p+1)*q^2; A330819:=[op(A330819), x]; fi;

od;

od;

A330819;

MATHEMATICA

(m = 2^MersennePrimeExponent[Range[9]] - 1)^2 * (m + 2)^2 (* Amiram Eldar, Jan 03 2020 *)

CROSSREFS

Cf. A000043, A000668, A132794, A133049, A330817, A330818, A330820.

Sequence in context: A180697 A230065 A218813 * A297760 A167035 A167042

Adjacent sequences:  A330816 A330817 A330818 * A330820 A330821 A330822

KEYWORD

nonn

AUTHOR

Walter Kehowski, Jan 01 2020

STATUS

approved

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Last modified May 19 18:35 EDT 2022. Contains 353847 sequences. (Running on oeis4.)