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A056743
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a(n) = phi(2^prime(n) - 1)/prime(n); a(0) = 0 by convention.
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2
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0, 1, 2, 6, 18, 176, 630, 7710, 27594, 356960, 18407808, 69273666, 3697909056, 53630700752, 204064589160, 2992477516800, 169917983040000, 9770466930024800, 37800705069076950, 2202596295934991760
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OFFSET
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0,3
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LINKS
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MAPLE
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with numtheory; A056743 := proc(n) phi( 2^ithprime(n) - 1 )/ithprime(n); end;
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MATHEMATICA
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Phi( A001348) / A000040. Table[EulerPhi[(2^Prime[n] - 1)]/Prime[n], {n, 1, 25}]
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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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