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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; 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.)