login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

EXTENSIONS

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 11 03:15 EST 2016. Contains 279034 sequences.