OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
a(n) ~ exp(sqrt(2*n/3)*Pi) * (1/(4*sqrt(3))-3*sqrt(3)/(8*Pi^2)) * (1 - Pi*(135+2*Pi^2)/(24*(2*Pi^2-9)*sqrt(6*n))). - Vaclav Kotesovec, Nov 05 2016
EXAMPLE
For n = 6 we have:
--------------------------------------
. Sum of
Partitions repeated parts
--------------------------------------
6 .......................... 0
3 + 3 ...................... 6
4 + 2 ...................... 0
2 + 2 + 2 .................. 6
5 + 1 ...................... 0
3 + 2 + 1 .................. 0
4 + 1 + 1 .................. 2
2 + 2 + 1 + 1 .............. 6
3 + 1 + 1 + 1 .............. 3
2 + 1 + 1 + 1 + 1 .......... 4
1 + 1 + 1 + 1 + 1 + 1 ...... 6
--------------------------------------
Total ..................... 33
So a(6) = 33.
MAPLE
b:= proc(n, i) option remember; local h, j, t;
if n<0 then [0, 0]
elif n=0 then [1, 0]
elif i<1 then [0, 0]
else h:= [0, 0];
for j from 0 to iquo(n, i) do
t:= b(n-i*j, i-1);
h:= [h[1]+t[1], h[2]+t[2]+`if`(j<2, 0, t[1]*i*j)]
od; h
fi
end:
a:= n-> b(n, n)[2]:
seq(a(n), n=0..50); # Alois P. Heinz, Nov 20 2011
MATHEMATICA
b[n_, i_] := b[n, i] = Module[{h, j, t}, Which [n<0, {0, 0}, n==0, {1, 0}, i<1, {0, 0}, True, h = {0, 0}; For[j=0, j <= Quotient[n, i], j++, t = b[n - i*j, i-1]; h = {h[[1]] + t[[1]], h[[2]] + t[[2]] + If[j<2, 0, t[[1]]* i*j]}]; h]]; a[n_] := b[n, n][[2]]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Jan 15 2016, after Alois P. Heinz *)
Table[Total[Flatten[Select[Flatten[Split/@IntegerPartitions[n], 1], Length[ #]> 1&]]], {n, 0, 50}] (* Harvey P. Dale, Jan 24 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Nov 19 2011
EXTENSIONS
More terms from Alois P. Heinz, Nov 20 2011
STATUS
approved