A071804 Number of pairs (x,y) such that tau(x^y) = x+y, 1<=x<=n, 1<=y<=n.

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

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