OFFSET
1,2
COMMENTS
LINKS
G. C. Greubel, Rows n = 1..50 of the triangle, flattened
Wolfdieter Lang, First ten rows
FORMULA
T(n, k) = A051418(n) * (1 if k = 1 otherwise 1/k^2 - 1/(k-1)^2). - G. C. Greubel, Apr 26 2023
EXAMPLE
For n=2 the o.g.f. of A120072(m,2)/A120073(m,2) (=[5/36, 3/16, 21/100, 2/9, ...]) is G(x,2) = -dilog(1-x) + x*P(2,x)/(1*4*(1-x)) = -dilog(1-x) + x*(4-3*x)/(4*(1-x)).
Triangle begins:
1;
4, -3;
36, -27, -5;
144, -108, -20, -7;
3600, -2700, -500, -175, -81;
3600, -2700, -500, -175, -81, -44;
176400, -132300, -24500, -8575, -3969, -2156, -1300;
MATHEMATICA
Table[(Apply[LCM, Range[n]])^2*If[k==1, 1, (1-2*k)/(k*(k-1))^2], {n, 15}, {k, n}]//Flatten (* G. C. Greubel, Apr 26 2023 *)
PROG
(Magma)
f:= func< n | n eq 1 select 1 else 1/n^2 -1/(n-1)^2 >;
A120078:= func< n, k | (Lcm([1..n]))^2*f(k) >;
[A120078(n, k): k in [1..n], n in [1..15]]; // G. C. Greubel, Apr 26 2023
(SageMath)
def f(k): return 1 if (k==1) else 1/k^2 - 1/(k-1)^2
def A120078(n, k): return (lcm(range(1, n+1)))^2*f(k)
flatten([[A120078(n, k) for k in range(1, n+1)] for n in range(1, 16)]) # G. C. Greubel, Apr 26 2023
CROSSREFS
KEYWORD
sign,tabl
AUTHOR
Wolfdieter Lang, Jul 20 2006
STATUS
approved