id:A056743 - OEIS Search Results

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a(n) = phi(2^prime(n) - 1)/prime(n); a(0) = 0 by convention.

+0
2

0, 1, 2, 6, 18, 176, 630, 7710, 27594, 356960, 18407808, 69273666, 3697909056, 53630700752, 204064589160, 2992477516800, 169917983040000, 9770466930024800, 37800705069076950, 2202596295934991760 (list; graph; listen)

	OFFSET	`0,3`
	MAPLE	`with numtheory; A056743 := proc(n) phi( 2^ithprime(n) - 1 )/ithprime(n); end;`
	MATHEMATICA	`Phi( A001348) / A000040. Table[EulerPhi[(2^Prime[n] - 1)]/Prime[n], {n, 1, 25}]`
	CROSSREFS	`Cf. A000020, A064535.` `Sequence in context: A000138 A028857 A052687 this_sequence A064535 A128123 A058081` `Adjacent sequences: A056740 A056741 A056742 this_sequence A056744 A056745 A056746`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 14 2000`

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.

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