OFFSET
1,3
COMMENTS
Triangle A165674, which is the reversal of this triangle, is generated by the asymptotic expansion of the higher order exponential integral E(x,m=2,n). - Johannes W. Meijer, Oct 16 2009
LINKS
G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
FORMULA
EXAMPLE
Triangle begins:
1
1 3
1 5 11
1 7 26 50
1 9 47 154 274
...
a(5, 3) = 4*3*2+5*3*2+5*4*2+5*4*3 = 154.
MATHEMATICA
T[n_, 0] := 1; T[n_, k_]:= Product[i, {i, n - k, n}]*Sum[1/i, {i, n - k, n}]; Table[T[n, k], {n, 1, 10}, {k, 0, n - 1}] (* G. C. Greubel, Jan 21 2017 *)
PROG
(PARI) a(n, k) = prod(i=n-k, n, i)*sum(i=n-k, n, 1/i);
tabl(nn) = for (n=1, nn, for (k=0, n-1, print1(a(n, k), ", ")); print()); \\ Michel Marcus, Jan 21 2017
CROSSREFS
KEYWORD
AUTHOR
Amarnath Murthy, Apr 24 2004
EXTENSIONS
Edited and extended by David Wasserman, Apr 24 2007
STATUS
approved