OFFSET
1,1
COMMENTS
Inverse sums of second array terms by rows = 1/1, 1/4, 1/9, 1/16, ...; =
Sum_{n>=1} 1/a(n) = Pi^2/6 = 1.6449340668...
FORMULA
Triangle read by rows, antidiagonals of a secondary array.
The first array = sequences of the form a(n) = N*a(n-1) + a(n-2).
N = 1: 1, 1, 2, 3, ...;
N = 2: 1, 2, 5, 12, ...;
N = 3: 1, 3, 10, 33, ...;
...
The second array = (for N = 1,2,3,...) k(1)*k(3), k(2)*k(4), k(3)*k(5), ...:
2, 3, 10, 24, ...
5, 24, 145, 840, ...
10, 99, 1090, 11880, ...
The triangle = antidiagonals of this second array.
EXAMPLE
First few rows of the triangle:
2;
5, 3;
10, 24, 10;
17, 99, 145, 24;
26, 288, 1090, 840, 65;
37, 675, 5185, 11880, 4901, 168;
50, 1368, 18226, 93024, 129601, 28560, 442;
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson, Mar 30 2008
STATUS
approved