OFFSET
1,5
COMMENTS
The rule of building products is (a,b)*(x,y) = (a*x,b*y).
The number of divisors of (n,k) is A143235(n,k)-1, where the subtraction of 1 means that the unit (1,1) is not admitted here. - R. J. Mathar, Nov 30 2017
LINKS
R. J. Mathar, Table of n, a(n) for n = 1..1711, the first 59 diagonals.
R. J. Mathar, Java Source code of 2 files to generate the b-file
FORMULA
Dirichlet g.f.: A(s, t) = exp(B(s, t)/1 + B(2*s, 2*t)/2 + B(3*s, 3*t)/3 + ...) where B(s, t) = zeta(s)*zeta(t)-1.
EXAMPLE
1 1 1 2 1 ...
1 2 2 4 2 ...
1 2 2 4 2 ...
2 4 4 9 4 ...
1 2 2 4 2 ...
(6,2)=(6,1)*(1,2)=(3,2)*(2,1)=(3,1)*(2,2)=(1,2)*(6,1), so a(6,2)=5.
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Christian G. Bower, Jun 03 2005
STATUS
approved