login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A306435 Number of distinct integers that are product of the parts of exactly one partition of n into 3 positive parts. 2
0, 0, 0, 1, 1, 2, 3, 4, 5, 7, 8, 10, 12, 12, 12, 19, 19, 22, 27, 28, 31, 31, 38, 42, 46, 50, 50, 57, 51, 64, 71, 70, 77, 85, 86, 84, 104, 104, 108, 108, 123, 122, 119, 136, 147, 158, 156, 164, 170, 162, 194, 195, 193, 205, 219, 228, 215, 233, 254, 254, 278 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,6
LINKS
MAPLE
a:= proc(n) option remember; local m, c, i, j, h, w;
m, c:= proc() 0 end, 0; forget(m);
for i to iquo(n, 3) do for j from i to iquo(n-i, 2) do
h:= i*j*(n-j-i); w:= m(h);
if w=0 then m(h):= 1; c:= c+1
elif w=1 then m(h):= 2; c:= c-1
fi
od od; c
end:
seq(a(n), n=0..80);
MATHEMATICA
a[n_] := a[n] = Module[{m, c = 0, i, j, h, w}, m[_] = 0; For[i = 1, i <= Quotient[n, 3], i++, For[j = i, j <= Quotient[n-i, 2], j++, h = i*j*(n - j - i); w = m[h]; If[w==0, m[h] = 1; c++; If[w==1, m[h] = 2; c--]]]]; c];
a /@ Range[0, 80] (* Jean-François Alcover, Dec 12 2020, after Alois P. Heinz *)
CROSSREFS
Column k=1 of A317578.
Sequence in context: A317296 A103740 A317578 * A034155 A306403 A129590
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 15 2019
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 05:16 EDT 2024. Contains 371264 sequences. (Running on oeis4.)