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A056742
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a(n) = phi(2^n - 1)/2.
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1
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1, 3, 4, 15, 18, 63, 64, 216, 300, 968, 864, 4095, 5292, 13500, 16384, 65535, 69984, 262143, 240000, 889056, 1320352, 4105040, 3317760, 16200000, 22358700, 56733696, 66382848, 266913216, 267300000, 1073741823, 1073741824
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OFFSET
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2,2
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LINKS
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FORMULA
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MATHEMATICA
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Table[EulerPhi[(2^n - 1)]/2, {n, 2, 40}]
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PROG
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(PARI) a(n) = eulerphi(2^n - 1)/2; \\ Amiram Eldar, Jun 09 2024
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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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