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A275630
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a(n) = product of distinct primes dividing prime(n)^2 - 1.
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2
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3, 2, 6, 6, 30, 42, 6, 30, 66, 210, 30, 114, 210, 462, 138, 78, 870, 930, 1122, 210, 222, 390, 1722, 330, 42, 510, 1326, 318, 330, 798, 42, 4290, 2346, 4830, 1110, 570, 6162, 246, 3486, 7482, 2670, 2730, 570, 582, 462, 330, 11130, 1554, 12882, 13110, 2262, 3570, 330, 210, 258, 8646, 2010
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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a[n_] := Times @@ FactorInteger[Prime[n]^2 - 1][[;; , 1]]; Array[a, 60] (* Amiram Eldar, Jan 30 2021 *)
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PROG
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(PARI) a(n) = factorback(factorint(prime(n)^2-1)[, 1]); \\ Michel Marcus, Jan 30 2021
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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