login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A071804 Number of pairs (x,y) such that tau(x^y) = x+y, 1<=x<=n, 1<=y<=n. 0
0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

LINKS

Table of n, a(n) for n=1..105.

PROG

(PARI) for(n=1, 130, print1(sum(i=1, n, sum(j=1, n, if(numdiv(i^j)-i-j, 0, 1))), ", "))

CROSSREFS

Cf. A000005.

Sequence in context: A067100 A296237 A074802 * A280953 A111894 A279012

Adjacent sequences:  A071801 A071802 A071803 * A071805 A071806 A071807

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jun 06 2002

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 11 16:13 EDT 2021. Contains 342886 sequences. (Running on oeis4.)