A182713
Number of 3's in the last section of the set of partitions of n.
Original entry on oeis.org
0, 0, 1, 0, 1, 2, 2, 3, 6, 6, 10, 14, 18, 24, 35, 42, 58, 76, 97, 124, 164, 202, 261, 329, 412, 514, 649, 795, 992, 1223, 1503, 1839, 2262, 2741, 3346, 4056, 4908, 5919, 7150, 8568, 10297, 12320, 14721, 17542, 20911, 24808, 29456, 34870, 41232, 48652, 57389
Offset: 1
a(7) = 2 counts the 3's in 7 = 4+3 = 3+2+2. The 3's in 7 = 3+3+1 = 3+2+1+1 = 3+1+1+1+1 do not count.
From _Omar E. Pol_, Oct 27 2012: (Start)
--------------------------------------
Last section Number
of the set of of
partitions of 7 3's
--------------------------------------
7 .............................. 0
4 + 3 .......................... 1
5 + 2 .......................... 0
3 + 2 + 2 ...................... 1
. 1 .......................... 0
. 1 ...................... 0
. 1 ...................... 0
. 1 .................. 0
. 1 ...................... 0
. 1 .................. 0
. 1 .................. 0
. 1 .............. 0
. 1 .............. 0
. 1 .......... 0
. 1 ...... 0
------------------------------------
. 5 - 3 = 2
.
In the last section of the set of partitions of 7 the difference between the sum of the third column and the sum of the fourth column is 5 - 3 = 2 equaling the number of 3's, so a(7) = 2 (see also A024787).
(End)
-
b:= proc(n, i) option remember; local g, h;
if n=0 then [1, 0]
elif i<2 then [0, 0]
else g:= b(n, i-1); h:= `if`(i>n, [0, 0], b(n-i, i));
[g[1]+h[1], g[2]+h[2]+`if`(i=3, h[1], 0)]
fi
end:
a:= n-> b(n, n)[2]:
seq(a(n), n=1..70); # Alois P. Heinz, Mar 18 2012
-
z = 60; f[n_] := f[n] = IntegerPartitions[n]; t1 = Table[Count[f[n], p_ /; Count[p, 1] < Count[p, 2]], {n, 0, z}] (* Clark Kimberling, Mar 31 2014 *)
b[n_, i_] := b[n, i] = Module[{g, h}, If[n == 0, {1, 0}, If[i<2, {0, 0}, g = b[n, i-1]; h = If[i>n, {0, 0}, b[n-i, i]]; Join[g[[1]] + h[[1]], g[[2]] + h[[2]] + If[i == 3, h[[1]], 0]]]]]; a[n_] := b[n, n][[2]]; Table[a[n], {n, 1, 70}] (* Jean-François Alcover, Nov 30 2015, after Alois P. Heinz *)
Table[Count[Flatten@Cases[IntegerPartitions[n], x_ /; Last[x] != 1], 3], {n, 51}] (* Robert Price, May 15 2020 *)
-
A182713 = lambda n: sum(list(p).count(3) for p in Partitions(n) if 1 not in p) # D. S. McNeil, Nov 29 2010
A182994
Sum of all parts of the n-th subshell of the head of the last section of the set of partitions of any even integer >= 2n.
Original entry on oeis.org
2, 6, 16, 32, 64, 132, 224, 404, 704, 1156, 1880, 3060, 4748, 7396, 11346, 17054, 25454, 37706, 54980, 79756, 114702, 163394, 231288, 325408, 454138, 630542, 870504, 1194536, 1631196, 2216992, 2997542, 4036022, 5411108, 7223636
Offset: 1
a(5)=64 because the 5th subshell of the head of the last section of any even integer >= 10 looks like this:
(10 . . . . . . . . . )
( 5 . . . . 5 . . . . )
( 6 . . . . . 4 . . . )
( 7 . . . . . . 3 . . )
( 4 . . . 3 . . 3 . . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
There are 17 parts whose sum is 10+5+5+6+4+7+3+4+3+3+2+2+2+2+2+2+2 = 10*5 + 2*7 = 64, so a(5)=64.
More terms from Omar E. Pol, Mar 03 2011
A182995
Sum of parts of the n-th subsection of the head of the last section of the set of partitions of any odd integer >= 2n+1.
Original entry on oeis.org
3, 7, 18, 44, 82, 158, 303, 507, 873, 1470, 2354, 3756, 5923, 9065, 13815, 20824, 30853, 45365, 66210, 95415, 136696, 194414, 274057, 384136, 535219, 740559, 1019529, 1396212, 1901533, 2577918, 3479291, 4673711, 6253003, 8332767
Offset: 1
a(5)=82 because the 5th subsection of the head of the last section of any odd integer >= 11 looks like this:
(11 . . . . . . . . . . )
( 6 . . . . . 5 . . . . )
( 7 . . . . . . 4 . . . )
( 8 . . . . . . . 3 . . )
( 4 . . . 4 . . . 3 . . )
( 5 . . . . 3 . . 3 . . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
. (2 . )
There are 21 parts whose sum is 11+6+5+7+4+8+3+4+4+3+5+3+3+2+2+2+2+2+2+2+2 = 11*6 + 2*8 = 82, so a(5) = 82.
a(17) corrected and more terms from Omar E. Pol, Mar 03 2011.
A193827
Irregular triangle read by rows in which row n lists the emergent parts of all partitions of n, or 0 if such parts do not exist.
Original entry on oeis.org
0, 0, 0, 0, 2, 3, 2, 2, 4, 3, 3, 2, 5, 4, 2, 2, 4, 3, 2, 2, 3, 6, 5, 4, 3, 2, 5, 4, 2, 2, 3, 7, 3, 3, 6, 5, 2, 2, 4, 3, 2, 2, 3, 6, 5, 4, 2, 2, 2, 2, 3, 4, 8, 4, 3, 7, 6, 5, 3, 2, 5, 4, 2, 2, 3, 7, 3, 3, 6, 5, 2, 2, 2, 2, 3, 3, 4, 9, 5, 4, 3, 4, 8, 7, 6
Offset: 0
If written as a triangle:
0,
0,
0,
0,
2,
3,
2,2,4,3,
3,2,5,4,
2,2,4,3,2,2,3,6,5,4,
3,2,5,4,2,2,3,7,3,3,6,5,
2,2,4,3,2,2,3,6,5,4,2,2,2,2,3,4,8,4,3,7,6,5,
3,2,5,4,2,2,3,7,3,3,6,5,2,2,2,2,3,3,4,9,5,4,3,4,8,7,6
A194714
Sum of all odd-indexed parts minus the sum of all even-indexed parts of all partitions of n, with the parts written in nondecreasing order.
Original entry on oeis.org
1, 2, 3, 4, 5, 8, 9, 14, 18, 26, 32, 48, 57, 82, 102, 138, 169, 230, 278, 370, 450, 584, 709, 914, 1102, 1400, 1692, 2124, 2555, 3186, 3818, 4720, 5649, 6926, 8269, 10078, 11989, 14526, 17249, 20782, 24603, 29508, 34843, 41600, 49008, 58258, 68468, 81098
Offset: 1
a(6) = 37 - 29 = 8 because the partitions of 6 written in nondecreasing order are
.
. 6 = 6
. 3 - 3 = 0
. 2 - 4 = -2
. 2 - 2 + 2 = 2
. 1 - 5 = -4
. 1 - 2 + 3 = 2
. 1 - 1 + 4 = 4
. 1 - 1 + 2 - 2 = 0
. 1 - 1 + 1 - 3 = -2
. 1 - 1 + 1 - 1 + 2 = 2
. 1 - 1 + 1 - 1 + 1 - 1 = 0
----------------------------------
. 20 - 21 + 14 - 7 + 3 - 1 = 8
A207034
Sum of all parts minus the number of parts of the n-th partition in the list of colexicographically ordered partitions of j, if 1<=n<=A000041(j).
Original entry on oeis.org
0, 1, 2, 2, 3, 3, 4, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8, 5, 6, 6, 7, 7, 7, 8, 7, 8, 8, 8, 9, 6, 7, 7, 8, 7, 8, 8, 9, 8, 8, 9, 9, 9, 10, 6, 7, 7, 8, 8, 8, 9, 8, 9, 9, 9, 10, 8, 9, 9, 10, 9, 10, 10, 10, 11, 7, 8, 8, 9, 8, 9
Offset: 1
Illustration of initial terms, n = 1..15. Consider the last 15 rows of the tail of the last section of the set of partitions in colexicographic order of any integer >= 8. The tail contains at least A000041(8-1) = 15 parts of size 1. a(n) is also the number of dots in the n-th row of the diagram.
----------------------------------
n Tail a(n)
----------------------------------
15 1 . . . . . . 6
14 1 . . . . . 5
13 1 . . . . . 5
12 1 . . . . 4
11 1 . . . . . 5
10 1 . . . . 4
9 1 . . . . 4
8 1 . . . 3
7 1 . . . . 4
6 1 . . . 3
5 1 . . . 3
4 1 . . 2
3 1 . . 2
2 1 . 1
1 1 0
----------------------------------
Written as a triangle:
0;
1;
2;
2,3;
3,4;
3,4,4,5;
4,5,5,6;
4,5,5,6,6,6,7;
5,6,6,7,6,7,7,8;
5,6,6,7,7,7,8,7,8,8,8,9;
6,7,7,8,7,8,8,9,8,8,9,9,9,10;
6,7,7,8,8,8,9,8,9,9,9,10,8,9,9,10,9,10,10,10,11;
...
Consider a matrix [j X A000041(j)] in which the rows represent the partitions of j in colexicographic order (see A211992). Every part of every partition is located in a cell of the matrix. We can see that a(n) is the number of empty cells in row n for any integer j, if A000041(j) >= n. The number of empty cells in row n equals the sum of all parts minus the number of parts in the n-th partition of j.
Illustration of initial terms. The smallest part of every partition is located in the last column of the matrix.
---------------------------------------------------------
. j: 1 2 3 4 5 6
n a(n)
---------------------------------------------------------
1 0 | 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 | . 2 . 2 1 . 2 1 1 . 2 1 1 1 . 2 1 1 1 1
3 2 | . . 3 . . 3 1 . . 3 1 1 . . 3 1 1 1
4 2 | . . 2 2 . . 2 2 1 . . 2 2 1 1
5 3 | . . . 4 . . . 4 1 . . . 4 1 1
6 3 | . . . 3 2 . . . 3 2 1
7 4 | . . . . 5 . . . . 5 1
8 3 | . . . 2 2 2
9 4 | . . . . 4 2
10 4 | . . . . 3 3
11 5 | . . . . . 6
...
Illustration of initial terms. In this case the largest part of every partition is located in the first column of the matrix.
---------------------------------------------------------
. j: 1 2 3 4 5 6
n a(n)
---------------------------------------------------------
1 0 | 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 | 2 . 2 1 . 2 1 1 . 2 1 1 1 . 2 1 1 1 1 .
3 2 | 3 . . 3 1 . . 3 1 1 . . 3 1 1 1 . .
4 2 | 2 2 . . 2 2 1 . . 2 2 1 1 . .
5 3 | 4 . . . 4 1 . . . 4 1 1 . . .
6 3 | 3 2 . . . 3 2 1 . . .
7 4 | 5 . . . . 5 1 . . . .
8 3 | 2 2 2 . . .
9 4 | 4 2 . . . .
10 4 | 3 3 . . . .
11 5 | 6 . . . . .
...
Cf.
A135010,
A138121,
A141285,
A182703,
A194548,
A196087,
A207031,
A207032,
A207035,
A211992,
A228716,
A230440.
A210979
Total area of the shadows of the three views of the version "Tree" of the shell model of partitions with n shells.
Original entry on oeis.org
0, 3, 8, 15, 27, 42, 69, 102, 155, 225, 327, 458, 652, 894, 1232, 1669, 2257, 2999, 3996, 5242, 6877, 8928, 11564, 14845, 19045, 24223, 30756, 38815, 48877, 61195, 76496, 95124, 118067, 145930, 179991, 221160, 271268, 331538, 404463, 491948, 597253
Offset: 0
For n = 7 the three views of the shell model of partitions version "tree" with seven shells looks like this:
.
. A194805(7) = 25 A006128(7) = 54
.
. 7 7
. 4 4 3
. 5 5 2
. 3 3 2 2
. 6 1 6 1
. 3 1 3 3 1
. 4 1 4 2 1
. 2 1 2 2 2 1
. 1 5 5 1 1
. 1 3 3 2 1 1
. 4 1 4 1 1 1
. 2 1 2 2 1 1 1
. 1 3 3 1 1 1 1
. 2 1 2 1 1 1 1 1
. 1 1 1 1 1 1 1 1
-------------------------------------------------
.
. 6 3 4 2 1 3 5 4 7
. 3 2 2 1 2 2 3
. 2 1 2
. 1
. 1
. 1
. 1
.
. A194803(7) = 23
.
The areas of the shadows of the three views are A006128(7) = 54, A194803(7) = 23 and A194805(7) = 25, therefore the total area of the three shadows is 54+23+25 = 102, so a(7) = 102.
A220482
Triangle read by rows: T(j,k) in which row j lists the parts in nondecreasing order of the j-th region of the set of partitions of n, with 1<=j<=A000041(n).
Original entry on oeis.org
1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 4, 3, 1, 1, 1, 1, 1, 2, 5, 2, 2, 4, 3, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 6, 3, 2, 5, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 7, 2, 2, 4, 3, 2, 2, 3, 6, 5, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 4, 8
Offset: 1
First 15 rows of the irregular triangle are
1;
1, 2;
1, 1, 3;
2;
1, 1, 1, 2, 4;
3;
1, 1, 1, 1, 1, 2, 5;
2;
2, 4;
3;
1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 6;
3;
2, 5;
4;
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 7;
A228350
Triangle read by rows: T(j,k) is the k-th part in nonincreasing order of the j-th region of the set of compositions (ordered partitions) of n in colexicographic order, if 1<=j<=2^(n-1) and 1<=k<=A006519(j).
Original entry on oeis.org
1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 4, 3, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 4, 3, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 6, 5, 4, 4, 3, 3
Offset: 1
---------------------------------------------------------
. Diagram Triangle
Compositions of of compositions (rows)
. of 5 regions and regions (columns)
----------------------------------------------------------
. _ _ _ _ _
. 5 |_ | 5
. 1+4 |_|_ | 1 4
. 2+3 |_ | | 2 3
. 1+1+3 |_|_|_ | 1 1 3
. 3+2 |_ | | 3 2
. 1+2+2 |_|_ | | 1 2 2
. 2+1+2 |_ | | | 2 1 2
. 1+1+1+2 |_|_|_|_ | 1 1 1 2
. 4+1 |_ | | 4 1
. 1+3+1 |_|_ | | 1 3 1
. 2+2+1 |_ | | | 2 2 1
. 1+1+2+1 |_|_|_ | | 1 1 2 1
. 3+1+1 |_ | | | 3 1 1
. 1+2+1+1 |_|_ | | | 1 2 1 1
. 2+1+1+1 |_ | | | | 2 1 1 1
. 1+1+1+1+1 |_|_|_|_|_| 1 1 1 1 1
.
Also the structure could be represented by an isosceles triangle in which the n-th diagonal gives the n-th region. For the composition of 4 see below:
. _ _ _ _
. 4 |_ | 4
. 1+3 |_|_ | 1 3
. 2+2 |_ | | 2 2
. 1+1+2 |_|_|_ | 1 1 2
. 3+1 |_ | | 3 1
. 1+2+1 |_|_ | | 1 2 1
. 2+1+1 |_ | | | 2 1 1
. 1+1+1+1 |_|_|_|_| 1 1 1 1
.
Illustration of the four sections of the set of compositions of 4:
. _ _ _ _
. |_ | 4
. |_|_ | 1+3
. |_ | | 2+2
. _ _ _ |_|_|_ | 1+1+2
. |_ | 3 | | 1
. _ _ |_|_ | 1+2 | | 1
. _ |_ | 2 | | 1 | | 1
. |_| 1 |_| 1 |_| 1 |_| 1
.
.
Illustration of initial terms. The parts of the eight regions of the set of compositions of 4:
--------------------------------------------------------
\j: 1 2 3 4 5 6 7 8
k
--------------------------------------------------------
. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
1 |_|1 |_ |2 |_|1 |_ |3 |_|1 |_ |2 |_|1 |_ |4
2 |_|1 |_ |2 |_|1 |_ |3
3 | |1 | |2
4 |_|1 |_ |2
5 | |1
6 | |1
7 | |1
8 |_|1
.
Triangle begins:
1;
2,1;
1;
3,2,1,1;
1;
2,1;
1;
4,3,2,2,1,1,1,1;
1;
2,1;
1;
3,2,1,1;
1;
2,1;
1;
5,4,3,3,2,2,2,2,1,1,1,1,1,1,1,1;
...
.
Also triangle read by rows T(n,m) in which row n lists the parts of the n-th section of the set of compositions of the integers >= n, ordered by regions. Row lengths give A045623. Row sums give A001792 (see below):
[1];
[2,1];
[1],[3,2,1,1];
[1],[2,1],[1],[4,3,2,2,1,1,1,1];
[1],[2,1],[1],[3,2,1,1],[1],[2,1],[1],[5,4,3,3,2,2,2,2,1,1,1,1,1,1,1,1];
Cf.
A001787,
A001792,
A011782,
A029837,
A045623,
A065120,
A070939,
A135010,
A141285,
A187816,
A187818,
A193870,
A206437,
A228347,
A228348,
A228349,
A228351,
A228366,
A228367,
A228370,
A228371,
A228525,
A228526.
A340011
Irregular triangle read by rows T(n,k) in which row n lists n blocks, where the m-th block consists of the j-th row of triangle A127093 but with every term multiplied by A000041(m-1), where j = n - m + 1 and 1 <= m <= n.
Original entry on oeis.org
1, 1, 2, 1, 1, 0, 3, 1, 2, 2, 1, 2, 0, 4, 1, 0, 3, 2, 4, 3, 1, 0, 0, 0, 5, 1, 2, 0, 4, 2, 0, 6, 3, 6, 5, 1, 2, 3, 0, 0, 6, 1, 0, 0, 0, 5, 2, 4, 0, 8, 3, 0, 9, 5, 10, 7, 1, 0, 0, 0, 0, 0, 7, 1, 2, 3, 0, 0, 6, 2, 0, 0, 0, 10, 3, 6, 0, 12, 5, 0, 15, 7, 14, 11, 1, 2, 0, 4, 0, 0, 0, 8
Offset: 1
Triangle begins:
[1];
[1, 2], [1];
[1, 0, 3], [1, 2], [2];
[1, 2, 0, 4], [1, 0, 3], [2, 4], [3];
[1, 0, 0, 0, 5], [1, 2, 0, 4], [2, 0, 6], [3, 6], [5];
[...
Row sums give A066186.
Written as an irregular tetrahedron the first five slices are:
--
1;
-----
1, 2,
1;
--------
1, 0, 3,
1, 2,
2;
-----------
1, 2, 0, 4,
1, 0, 3,
2, 4,
3;
--------------
1, 0, 0, 0, 5,
1, 2, 0, 4,
2, 0, 6,
3, 6,
5;
--------------
Row sums give A339106.
The following table formed by four zones shows the correspondence between divisor and parts (n = 1..5):
.
|---|---------|-----|-------|---------|-----------|-------------|
| n | | 1 | 2 | 3 | 4 | 5 |
|---|---------|-----|-------|---------|-----------|-------------|
| P | | | | | | |
| A | | | | | | |
| R | | | | | | |
| T | | | | | | 5 |
| I | | | | | | 3 2 |
| T | | | | | 4 | 4 1 |
| I | | | | | 2 2 | 2 2 1 |
| O | | | | 3 | 3 1 | 3 1 1 |
| N | | | 2 | 2 1 | 2 1 1 | 2 1 1 1 |
| S | | 1 | 1 1 | 1 1 1 | 1 1 1 1 | 1 1 1 1 1 |
|---|---------|-----|-------|---------|-----------|-------------|
.
|---|---------|-----|-------|---------|-----------|-------------|
| | A181187 | 1 | 3 1 | 6 2 1 | 12 5 2 1 | 20 8 4 2 1 |
| L | | | | |/| | |/|/| | |/|/|/| | |/|/|/|/| |
| I | A066633 | 1 | 2 1 | 4 1 1 | 7 3 1 1 | 12 4 2 1 1 |
| N | | * | * * | * * * | * * * * | * * * * * |
| K | A002260 | 1 | 1 2 | 1 2 3 | 1 2 3 4 | 1 2 3 4 5 |
| | | = | = = | = = = | = = = = | = = = = = |
| | A138785 | 1 | 2 2 | 4 2 3 | 7 6 3 4 | 12 8 6 4 5 |
|---|---------|-----|-------|---------|-----------|-------------|
.
|---|---------|-----|-------|---------|-----------|-------------|
| | A127093 | 1 | 1 2 | 1 0 3 | 1 2 0 4 | 1 0 0 0 5 |
| |---------|-----|-------|---------|-----------|-------------|
| | A127093 | | 1 | 1 2 | 1 0 3 | 1 2 0 4 |
| |---------|-----|-------|---------|-----------|-------------|
| D | A127093 | | | 1 | 1 2 | 1 0 3 |
| I | A127093 | | | 1 | 1 2 | 1 0 3 |
| V |---------|-----|-------|---------|-----------|-------------|
| I | A127093 | | | | 1 | 1 2 |
| S | A127093 | | | | 1 | 1 2 |
| O | A127093 | | | | 1 | 1 2 |
| R |---------|-----|-------|---------|-----------|-------------|
| S | A127093 | | | | | 1 |
| | A127093 | | | | | 1 |
| | A127093 | | | | | 1 |
| | A127093 | | | | | 1 |
| | A127093 | | | | | 1 |
|---|---------|-----|-------|---------|-----------|-------------|
.
|---|---------|-----|-------|---------|-----------|-------------|
| | A127093 | 1 | 1 2 | 1 0 3 | 1 2 0 4 | 1 0 0 0 5 |
| C | A127093 | | 1 | 1 2 | 1 0 3 | 1 2 0 4 |
| O | - | | | 2 | 2 4 | 2 0 6 |
| N | - | | | | 3 | 3 6 |
| D | - | | | | | 5 |
|---|---------|-----|-------|---------|-----------|-------------|
.
This lower zone of the table is a condensed version of the "divisors" zone.
Cf.
A000070,
A000041,
A002260,
A026792,
A027750,
A058399,
A066633,
A127093,
A135010,
A138121,
A138785,
A176206,
A181187,
A182703,
A207031,
A207383,
A211992,
A221529,
A221530,
A221531,
A221649,
A221650,
A237593,
A245095,
A302246,
A302247,
A336811,
A336812,
A337209,
A338156,
A339106,
A339258,
A339278,
A339304,
A340031,
A340032,
A340035,
A340061.
Comments