|
|
A144657
|
|
a(n) = Sum_{j = 1..n} Sum_{i = 1..n} (i + j)! / (i! * j!).
|
|
2
|
|
|
0, 2, 14, 62, 242, 912, 3418, 12854, 48602, 184736, 705410, 2704132, 10400574, 40116572, 155117490, 601080358, 2333606186, 9075135264, 35345263762, 137846528780, 538257874398, 2104098963676, 8233430727554, 32247603683052, 126410606437702, 495918532948052, 1946939425648058
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
Recurrence: (n+1)*(12*n-19)*a(n) = 2*(30*n^2 - 24*n - 19)*a(n-1) - (48*n^2 - 9*n - 7)*a(n-2) - 2*(2*n-3)*a(n-3). - Vaclav Kotesovec, Oct 20 2012
|
|
MATHEMATICA
|
Table[Sum[Sum[(i+j)!/i!/j!, {i, 1, n}], {j, 1, n}], {n, 0, 20}] (* corrected by Vaclav Kotesovec, Oct 20 2012 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|