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A083542
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a(n) = phi(n+1)*phi(n), product of totients of two consecutive integers.
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8
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1, 2, 4, 8, 8, 12, 24, 24, 24, 40, 40, 48, 72, 48, 64, 128, 96, 108, 144, 96, 120, 220, 176, 160, 240, 216, 216, 336, 224, 240, 480, 320, 320, 384, 288, 432, 648, 432, 384, 640, 480, 504, 840, 480, 528, 1012, 736, 672, 840, 640, 768, 1248, 936, 720, 960, 864, 1008
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OFFSET
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1,2
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LINKS
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FORMULA
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MAPLE
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a:= n-> (p-> p(n)*p(n+1))(numtheory[phi]):
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MATHEMATICA
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Times @@ EulerPhi@ # & /@ Partition[Range@ 58, 2, 1] (* Michael De Vlieger, Mar 25 2017 *)
Times@@@Partition[EulerPhi[Range[60]], 2, 1] (* Harvey P. Dale, Oct 29 2019 *)
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PROG
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(Haskell)
a083542 n = a000010 n * a000010 (n + 1)
a083542_list = zipWith (*) (tail a000010_list) a000010_list
(PARI) a(n) = eulerphi(n) * eulerphi(n+1); \\ Amiram Eldar, Jul 10 2024
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CROSSREFS
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KEYWORD
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nonn,easy,changed
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AUTHOR
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STATUS
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approved
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