A181844 Sum over all partitions of n of the LCM of the parts.

1, 1, 3, 6, 12, 23, 38, 73, 118, 198, 318, 530, 819, 1298, 1974, 2975, 4516, 6698, 9980, 14550, 21186, 30304, 43503, 62030, 87908, 123292, 172543, 239720, 331688, 458198, 629376, 860332, 1168172, 1583176, 2138438, 2876283, 3859770, 5159886, 6863702, 9112356

Offset: 0

Author

Peter Luschny, Dec 07 2010

Keywords

• nonn

Comments

Old name was: Row sums of A181842.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..188 (terms n=1..80 from Vincenzo Librandi)

Crossrefs

Cf. A078392 (the same for GCD), A181843, A181842, A256067, A256553, A256554, A306956.

Programs

Maple

with(combstruct):
a181844 := proc(n) local k,L,l,R,part;
R := NULL; L := 0;
for k from 1 to n do
   part := iterstructs(Partition(n),size=k):
   while not finished(part) do
      l := nextstruct(part);
      L := L + ilcm(op(l));
   od;
od;
L end:
# second Maple program:
b:= proc(n, i, r) option remember; `if`(n=0, r, `if`(i<1, 0,
       b(n, i-1, r)+b(n-i, min(i, n-i), ilcm(i, r))))
    end:
a:= n-> b(n$2, 1):
seq(a(n), n=0..42);  # Alois P. Heinz, Mar 18 2019

Mathematica

t[n_, k_] := LCM @@@ IntegerPartitions[n, {n - k + 1}] // Total; a[n_] := Sum[t[n, k], {k, 1, n}]; Table[a[n], {n, 1, 32}] (* Jean-François Alcover, Jul 26 2013 *)

Formula

a(n) = Sum_{k>=0} k * A256067(n,k) = Sum_{k>=0} A256553(n,k)*A256554(n,k). - Alois P. Heinz, Apr 02 2015

Extensions

a(0)=1 prepended by Alois P. Heinz, Mar 29 2015

New name from Alois P. Heinz, Mar 18 2019