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.

A026927 Number of partitions of n into an even number of parts, the greatest being 3; also, a(n+5) = number of partitions of n+2 into an odd number of parts, each <= 3.

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%I A026927 #21 Sep 07 2019 01:38:44
%S A026927 0,0,0,1,1,2,1,3,3,5,4,7,6,9,8,12,11,15,13,18,17,22,20,26,24,30,28,35,
%T A026927 33,40,37,45,43,51,48,57,54,63,60,70,67,77,73,84,81,92,88,100,96,108,
%U A026927 104,117
%N A026927 Number of partitions of n into an even number of parts, the greatest being 3; also, a(n+5) = number of partitions of n+2 into an odd number of parts, each <= 3.
%F A026927 a(n) + A026923(n) = A069905(n). - _R. J. Mathar_, Aug 22 2019
%F A026927 Conjectures from _Colin Barker_, Sep 01 2019: (Start)
%F A026927 G.f.: x^4*(1 + x^2 - x^3 + x^4) / ((1 - x)^3*(1 + x)^2*(1 - x + x^2)*(1 + x^2)*(1 + x + x^2)).
%F A026927 a(n) = a(n-1) + a(n-4) - a(n-5) + a(n-6) - a(n-7) - a(n-10) + a(n-11) for n>11.
%F A026927 (End)
%e A026927 Figure 1: The partitions of n into 3 parts for n = 3, 4, ...
%e A026927                                                           1+1+8
%e A026927                                                    1+1+7  1+2+7
%e A026927                                                    1+2+6  1+3+6
%e A026927                                             1+1+6  1+3+5  1+4+5
%e A026927                                      1+1+5  1+2+5  1+4+4  2+2+6
%e A026927                               1+1+4  1+2+4  1+3+4  2+2+5  2+3+5
%e A026927                        1+1+3  1+2+3  1+3+3  2+2+4  2+3+4  2+4+4
%e A026927          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 A026927 -----------------------------------------------------------------------
%e A026927   n  |     3      4      5      6      7      8      9     10      ...
%e A026927 -----------------------------------------------------------------------
%e A026927 a(n) |     0      1      1      2      1      3      3      5      ...
%e A026927 -----------------------------------------------------------------------
%Y A026927 3rd column of A026921.
%Y A026927 Cf. A026923, A309683, A309684, A309685, A309686, A309687, A309688, A309689, A309690, A309692, A309694.
%K A026927 nonn
%O A026927 1,6
%A A026927 _Clark Kimberling_