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A080768 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. 2
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; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

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).

LINKS

Table of n, a(n) for n=0..29.

CROSSREFS

Cf. A047994, A080766, A080767, A067739, A067741.

Sequence in context: A080017 A042551 A059188 * A203578 A047067 A185895

Adjacent sequences:  A080765 A080766 A080767 * A080769 A080770 A080771

KEYWORD

nonn

AUTHOR

Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp)

EXTENSIONS

Kohmoto found 2nd, 6th, 13th, 25th terms. Dean Hickerson calculated the other terms.

STATUS

approved

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Last modified October 20 09:00 EDT 2014. Contains 248329 sequences.