id:A080768 - OEIS Search Results

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A unitary phi reciprocal amicable number: consider two different numbers a, b which satisfy the following equation for some integer k: uphi(a)=uphi(b)=1/k*a*b/(a-b); or equivalently, 1/uphi(a)=1/uphi(b)=k*(-1/a+1/b); sequence gives k numbers.

+0
3

2, 3, 14, 35, 22, 3, 242, 23, 253, 13, 155, 12, 3, 77, 5, 4, 65, 860, 3, 10882, 14, 91, 13, 5, 80, 543, 946, 25, 1350, 13 (list; graph; listen)

	OFFSET	`0,1`
	COMMENT	`Here uphi(n)=A047994(n) is the unitary totient function: if n = Product p_i^e_i, uphi(n) = Product (p_i^e_i - 1).`
	CROSSREFS	`Cf. A047994, A080766, A080767, A067739, A067741.` `Adjacent sequences: A080765 A080766 A080767 this_sequence A080769 A080770 A080771` `Sequence in context: A080017 A042551 A059188 this_sequence A047067 A128849 A141148`
	KEYWORD	`nonn`
	AUTHOR	`Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp)`
	EXTENSIONS	`Kohmoto found 2nd, 6th, 13th, 25th terms. Hickerson calculated the other terms.`

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Last modified October 7 14:39 EDT 2008. Contains 144666 sequences.

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