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.

A360672 Triangle read by rows where T(n,k) is the number of integer partitions of n whose left half (exclusive) sums to k, where k ranges from 0 to n.

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%I A360672 #13 Mar 11 2023 23:06:27
%S A360672 1,1,0,1,1,0,1,1,1,0,1,0,3,1,0,1,0,2,3,1,0,1,0,1,4,4,1,0,1,0,0,3,6,4,
%T A360672 1,0,1,0,0,1,7,7,5,1,0,1,0,0,1,4,8,10,5,1,0,1,0,0,0,3,6,14,11,6,1,0,1,
%U A360672 0,0,0,1,5,12,16,14,6,1,0
%N A360672 Triangle read by rows where T(n,k) is the number of integer partitions of n whose left half (exclusive) sums to k, where k ranges from 0 to n.
%C A360672 Also the number of integer partitions of n whose right half (inclusive) sums to n-k.
%e A360672 Triangle begins:
%e A360672   1
%e A360672   1  0
%e A360672   1  1  0
%e A360672   1  1  1  0
%e A360672   1  0  3  1  0
%e A360672   1  0  2  3  1  0
%e A360672   1  0  1  4  4  1  0
%e A360672   1  0  0  3  6  4  1  0
%e A360672   1  0  0  1  7  7  5  1  0
%e A360672   1  0  0  1  4  8 10  5  1  0
%e A360672   1  0  0  0  3  6 14 11  6  1  0
%e A360672   1  0  0  0  1  5 12 16 14  6  1  0
%e A360672   1  0  0  0  1  2 12 14 23 16  7  1  0
%e A360672   1  0  0  0  0  2  7 13 24 27 19  7  1  0
%e A360672   1  0  0  0  0  1  5  9 24 30 35 21  8  1  0
%e A360672   1  0  0  0  0  1  3  7 17 31 42 40 25  8  1  0
%e A360672   1  0  0  0  0  0  2  4 16 23 46 51 51 27  9  1  0
%e A360672   1  0  0  0  0  0  1  3 10 21 37 57 69 57 31  9  1  0
%e A360672   1  0  0  0  0  0  1  2  7 15 34 47 83 81 69 34 10  1  0
%e A360672 For example, row n = 9 counts the following partitions:
%e A360672   (9)  .  .  (333)  (432)        (54)        (63)      (72)    (81)
%e A360672                     (441)        (522)       (621)     (711)
%e A360672                     (22221)      (531)       (3321)    (4311)
%e A360672                     (111111111)  (3222)      (4221)    (5211)
%e A360672                                  (32211)     (33111)   (6111)
%e A360672                                  (2211111)   (42111)
%e A360672                                  (3111111)   (51111)
%e A360672                                  (21111111)  (222111)
%e A360672                                              (321111)
%e A360672                                              (411111)
%e A360672 For example, the partition y = (3,2,2,1,1) has left half (exclusive) (3,2), with sum 5, so y is counted under T(9,5).
%t A360672 Table[Length[Select[IntegerPartitions[n], Total[Take[#,Floor[Length[#]/2]]]==k&]],{n,0,10},{k,0,n}]
%Y A360672 Row sums are A000041.
%Y A360672 Column sums are A360673, inclusive A360671.
%Y A360672 The central diagonal T(2n,n) is A360674, ranks A360953.
%Y A360672 The left inclusive version is A360675 with rows reversed.
%Y A360672 A008284 counts partitions by length.
%Y A360672 A359893 and A359901 count partitions by median.
%Y A360672 First for prime indices, second for partitions, third for prime factors:
%Y A360672 - A360676 gives left sum (exclusive), counted by A360672, product A361200.
%Y A360672 - A360677 gives right sum (exclusive), counted by A360675, product A361201.
%Y A360672 - A360678 gives left sum (inclusive), counted by A360675, product A347043.
%Y A360672 - A360679 gives right sum (inclusive), counted by A360672, product A347044.
%Y A360672 Cf. A027193, A237363, A307683, A325347, A360005, A360071, A360254, A360616, A360682, A360686.
%K A360672 nonn,tabl
%O A360672 0,13
%A A360672 _Gus Wiseman_, Feb 27 2023