OFFSET
1,5
LINKS
C. G. Bower, Transforms (2)
FORMULA
EXAMPLE
Triangle begins:
1,
1, 1,
1, 3, 1,
1, 7, 6, 3,
1, 15, 25, 30, 12,
1, 31, 90, 195, 180, 60,
1, 63, 301, 1050, 1680, 1260, 360.
...
For row n = 4 we have the following "pies":
. 1
./ \
2 . 3 . 12 .. 12 . 123
.\ / .. / \ .(..)..(..)
. 4 .. 3--4 . 34 .. 4 .. (1234)
k=4 .. k=3 ..k=2 . k=2 . k=1
(3)....(6)...(3)..(4)... (1)
MAPLE
MATHEMATICA
A001710[n_] := If[n<2, 1, n!/2]; A008277[n_, k_] := StirlingS2[n, k]; A133800[n_, k_] := A008277[n, k]*A001710[k-1]; Table[A133800[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jan 20 2014, after R. J. Mathar *)
(* A (n >= 0, k >= 0)-based version: *)
A133800[n_, k_] := k! StirlingS2[n+1, k+1] / If[k>1, 2, 1];
Table[A133800[n, k], {n, 0, 9}, {k, 0, n}] // Flatten (* Peter Luschny, Oct 19 2017 *)
CROSSREFS
KEYWORD
AUTHOR
Barry Cipra and N. J. A. Sloane, Jan 17 2008
EXTENSIONS
More terms from R. J. Mathar, Jan 18 2008
STATUS
approved