cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A308265 Sum of the largest parts in the partitions of n into 3 parts.

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%I A308265 #9 Jun 15 2020 23:19:25
%S A308265 0,0,1,2,5,9,15,22,34,45,62,81,104,129,163,195,237,282,333,387,454,
%T A308265 518,596,678,768,862,973,1080,1205,1335,1475,1620,1786,1947,2130,2319,
%U A308265 2520,2727,2959,3185,3437,3696,3969,4249,4558,4860,5192,5532,5888,6252
%N A308265 Sum of the largest parts in the partitions of n into 3 parts.
%H A308265 <a href="/index/Par#part">Index entries for sequences related to partitions</a>
%F A308265 a(n) = Sum_{k=1..floor(n/3)} Sum_{i=k..floor((n-k)/2)} (n-i-k).
%F A308265 Conjectures from _Colin Barker_, Jul 16 2019: (Start)
%F A308265 G.f.: x^3*(1 + 2*x + 3*x^2 + 3*x^3 + 2*x^4) / ((1 - x)^4*(1 + x)^2*(1 + x + x^2)^2).
%F A308265 a(n) = 2*a(n-2) + 2*a(n-3) - a(n-4) - 4*a(n-5) - a(n-6) + 2*a(n-7) + 2*a(n-8) - a(n-10) for n>10.
%F A308265 (End)
%e A308265 Figure 1: The partitions of n into 3 parts for n = 3, 4, ...
%e A308265                                                           1+1+8
%e A308265                                                    1+1+7  1+2+7
%e A308265                                                    1+2+6  1+3+6
%e A308265                                             1+1+6  1+3+5  1+4+5
%e A308265                                      1+1+5  1+2+5  1+4+4  2+2+6
%e A308265                               1+1+4  1+2+4  1+3+4  2+2+5  2+3+5
%e A308265                        1+1+3  1+2+3  1+3+3  2+2+4  2+3+4  2+4+4
%e A308265          1+1+1  1+1+2  1+2+2  2+2+2  2+2+3  2+3+3  3+3+3  3+3+4    ...
%e A308265 -----------------------------------------------------------------------
%e A308265   n  |     3      4      5      6      7      8      9     10      ...
%e A308265 -----------------------------------------------------------------------
%e A308265 a(n) |     1      2      5      9     15     22     34     45      ...
%e A308265 -----------------------------------------------------------------------
%t A308265 Table[Sum[Sum[n - i - k, {i, k, Floor[(n - k)/2]}], {k, Floor[n/3]}], {n, 100}]
%Y A308265 Cf. A307872.
%K A308265 nonn
%O A308265 1,4
%A A308265 _Wesley Ivan Hurt_, May 17 2019