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A079704
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a(n) = 2*prime(n)^2.
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21
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8, 18, 50, 98, 242, 338, 578, 722, 1058, 1682, 1922, 2738, 3362, 3698, 4418, 5618, 6962, 7442, 8978, 10082, 10658, 12482, 13778, 15842, 18818, 20402, 21218, 22898, 23762, 25538, 32258, 34322, 37538, 38642, 44402, 45602, 49298, 53138, 55778
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OFFSET
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1,1
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COMMENTS
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Numbers of the form 2*p^2 where p runs through the primes.
For these numbers m, there are precisely 5 groups of order m, hence this is a subsequence of A054397. If p = 2, these 5 groups of order 8 are described in example section of A054397, and when p is odd prime, the five corresponding groups are described in a comment of A143928. - Bernard Schott, Dec 11 2021
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REFERENCES
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Pascal Ortiz, Exercices d'Algèbre, Collection CAPES / Agrégation, Ellipses, problème 1.35, pp. 70-74, 2004.
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LINKS
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FORMULA
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EXAMPLE
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a(2) = prime(2)^2*2 = 3^2*2 = 9*2 = 18.
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MATHEMATICA
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PROG
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(PARI) forprime (p=2, 100, print1(p^2*2", "))
(Haskell)
(Python)
from sympy import primerange
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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