A080766 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 a numbers.

2, 6, 14, 21, 240, 240, 242, 5520, 5566, 6578, 10881, 13056, 14880, 15444, 46200, 47908, 57600, 60480, 65280, 65292, 91392, 152320, 169728, 239540, 285696, 399168, 665280, 702000, 941625, 1405404

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, A080767, A080768, A067739, A067741.

Sequence in context: A071122 A173724 A101572 * A262506 A228649 A268641

Adjacent sequences: A080763 A080764 A080765 * A080767 A080768 A080769

Keyword

nonn

Author

Yasutoshi Kohmoto

Extensions

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

Status

approved