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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: A355176 A346606 A059188 * A203578 A329442 A281486 Adjacent sequences: A080765 A080766 A080767 * A080769 A080770 A080771 KEYWORD nonn AUTHOR Yasutoshi Kohmoto EXTENSIONS Kohmoto found 2nd, 6th, 13th, 25th terms. Dean Hickerson calculated the other terms. STATUS approved

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Last modified June 7 22:39 EDT 2023. Contains 363157 sequences. (Running on oeis4.)