|
|
A188814
|
|
Sum of the "complements" of the integer partitions of n.
|
|
4
|
|
|
0, 0, 0, 1, 4, 12, 27, 57, 107, 192, 327, 538, 855, 1329, 2018, 3003, 4402, 6349, 9045, 12720, 17713, 24395, 33335, 45118, 60655, 80888, 107242, 141177, 184905, 240679, 311850, 401860, 515725, 658630, 838006, 1061561, 1340193, 1685271, 2112576, 2638727
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,5
|
|
COMMENTS
|
Consider the m x k rectangle corresponding to an integer partition p of n, where m is the greatest part of p and k is the number of parts of p. Fit the Ferrers diagram of p inside its corresponding rectangle. a(n) is the number of empty spaces in all such rectangles over all partitions of n.
|
|
REFERENCES
|
Sriram Pemmaraju and Steven Skiena, Computational Discrete Mathematics, Cambridge, 2003, page 145.
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
a(4) = 4 because the partitions 4, 2+2, 1+1+1+1 have no empty spaces while the partitions 3+1 and 2+1+1 each have two.
|
|
MAPLE
|
b:= proc(n, i) option remember; local f, g;
if n=0 or i=1 then [1, n]
elif i<1 then [0, 0]
else f:= b(n, i-1); g:= `if`(i>n, [0, 0], b(n-i, i));
[f[1]+g[1], f[2]+g[2]+g[1]]
fi
end:
a:= n-> add(add(i, i=b(n-j, min(j, n-j)))*j, j=1..n) -n*b(n, n)[1]:
|
|
MATHEMATICA
|
f[list_]:= Total[Select[Reverse[Table[Max[list]-list[[i]], {i, 1, Length[list]}]], #>0&]];
Table[Total[Map[f, IntegerPartitions[n]]], {n, 0, 30}]
(* second program: *)
b[n_, i_] := b[n, i] = Module[{f, g}, If [n==0 || i==1, {1, n}, If[i<1, {0, 0}, f = b[n, i-1]; g = If[i>n, {0, 0}, b[n-i, i]]]; {f[[1]] + g[[1]], f[[2]] + g[[2]] + g[[1]]}]];
a[n_] := Sum[Sum[i, {i, b[n-j, Min[j, n-j]]}]*j, {j, 1, n}]-n*b[n, n][[1]];
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|