A340056
Irregular triangle read by rows T(n,k) in which row n lists n blocks, where the m-th block consists of the divisors of j multiplied by A000041(m-1), where j = n - m + 1 and 1 <= m <= n.
Original entry on oeis.org
1, 1, 2, 1, 1, 3, 1, 2, 2, 1, 2, 4, 1, 3, 2, 4, 3, 1, 5, 1, 2, 4, 2, 6, 3, 6, 5, 1, 2, 3, 6, 1, 5, 2, 4, 8, 3, 9, 5, 10, 7, 1, 7, 1, 2, 3, 6, 2, 10, 3, 6, 12, 5, 15, 7, 14, 11, 1, 2, 4, 8, 1, 7, 2, 4, 6, 12, 3, 15, 5, 10, 20, 7, 21, 11, 22, 15, 1, 3, 9, 1, 2, 4, 8, 2, 14, 3, 6, 9, 18, 5
Offset: 1
Triangle begins:
[1];
[1, 2], [1];
[1, 3], [1, 2], [2];
[1, 2, 4], [1, 3], [2, 4], [3];
[1, 5], [1, 2, 4], [2, 6], [3, 6], [5];
[...
The row sums of triangle give A066186.
Written as an irregular tetrahedron the first five slices are:
1;
-----
1, 2,
1;
-----
1, 3,
1, 2,
2;
--------
1, 2, 4,
1, 3,
2, 4,
3;
--------
1, 5,
1, 2, 4,
2, 6,
3, 6,
5;
--------
The row sums of tetrahedron give A339106.
The slices of the tetrahedron appear in 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 |
|---|---------|-----|-------|---------|-----------|-------------|
.
|---|---------|-----|-------|---------|-----------|-------------|
| | A027750 | 1 | 1 2 | 1 3 | 1 2 4 | 1 5 |
| |---------|-----|-------|---------|-----------|-------------|
| | A027750 | | 1 | 1 2 | 1 3 | 1 2 4 |
| |---------|-----|-------|---------|-----------|-------------|
| D | A027750 | | | 1 | 1 2 | 1 3 |
| I | A027750 | | | 1 | 1 2 | 1 3 |
| V |---------|-----|-------|---------|-----------|-------------|
| I | A027750 | | | | 1 | 1 2 |
| S | A027750 | | | | 1 | 1 2 |
| O | A027750 | | | | 1 | 1 2 |
| R |---------|-----|-------|---------|-----------|-------------|
| S | A027750 | | | | | 1 |
| | A027750 | | | | | 1 |
| | A027750 | | | | | 1 |
| | A027750 | | | | | 1 |
| | A027750 | | | | | 1 |
|---|---------|-----|-------|---------|-----------|-------------|
.
|---|---------|-----|-------|---------|-----------|-------------|
| | A027750 | 1 | 1 2 | 1 3 | 1 2 4 | 1 5 |
| C | A027750 | | 1 | 1 2 | 1 3 | 1 2 4 |
| O | - | | | 2 | 2 4 | 2 6 |
| N | - | | | | 3 | 3 6 |
| D | - | | | | | 5 |
|---|---------|-----|-------|---------|-----------|-------------|
.
The lower zone 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,
A245095,
A221649,
A221650,
A237593,
A302246,
A302247,
A336811,
A336812,
A337209,
A338156,
A339106,
A339258,
A339278,
A339304,
A340061.
A206555
Number of 5's in the last section of the set of partitions of n.
Original entry on oeis.org
0, 0, 0, 0, 1, 0, 1, 1, 2, 3, 4, 5, 8, 10, 15, 18, 26, 32, 44, 56, 73, 92, 120, 149, 193, 238, 302, 373, 469, 576, 716, 876, 1081, 1316, 1615, 1954, 2383, 2875, 3483, 4188, 5048, 6043, 7253, 8653, 10341, 12293, 14634, 17340, 20567, 24300, 28717, 33830
Offset: 1
A206560
Number of 10's in the last section of the set of partitions of n.
Original entry on oeis.org
0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 2, 2, 4, 4, 7, 8, 13, 14, 22, 25, 36, 43, 59, 70, 95, 113, 150, 179, 232, 278, 356, 426, 537, 644, 803, 960, 1189, 1417, 1739, 2072, 2523, 2999, 3631, 4304, 5181, 6130, 7342, 8662, 10330, 12159, 14437, 16958
Offset: 1
A210980
Total area of the shadows of the three views of the shell model of partitions, version "Tree", with n shells.
Original entry on oeis.org
0, 3, 10, 21, 42, 69, 123, 189, 304, 458, 693, 998, 1474, 2067, 2927, 4056, 5613, 7595, 10335, 13782, 18411, 24276, 31944, 41583, 54152, 69762, 89758, 114668, 146181, 185083, 234051, 294126, 368992, 460669, 573906, 711865, 881506, 1087023, 1338043
Offset: 0
For n = 7 the shadows of the three views of the shell model of partitions version "tree" with seven shells looks like this:
. | Partitions
. A194805(7) = 25 A066186(7) = 105 | of 7
. |
. 1 * * * * * * 1 | 7
. 2 * * * 1 * * 2 | 4+3
. 2 * * * * 1 * 2 | 5+2
. 3 * * 1 * 2 * 3 | 3+2+2
. 1 2 * * * * * 1 2 | 6+1
. 2 3 * * 1 * * 2 3 | 3+3+1
. 2 3 * * * 1 * 2 3 | 4+2+1
. 3 4 * 1 * 2 * 3 4 | 2+2+2+1
. 3 1 * * * * 1 2 3 | 5+1+1
. 4 2 * * 1 * 2 3 4 | 3+2+1+1
. 1 4 * * * 1 2 3 4 | 4+1+1+1
. 2 5 * 1 * 2 3 4 5 | 2+2+1+1+1
. 5 1 * * 1 2 3 4 5 | 3+1+1+1+1
. 1 6 * 1 2 3 4 5 6 | 2+1+1+1+1+1
. 7 1 2 3 4 5 6 7 | 1+1+1+1+1+1+1
. ---------------------------------- |
. |
. * * * * 1 * * * * |
. * * * 1 2 * * * * |
. * 1 * * 2 1 * * * |
. * * 1 2 2 * * 1 * |
. * * * * 2 2 1 * * |
. 1 2 2 3 2 * * * * |
. 2 3 2 2 1 |
. |
. A194804(7) = 59 |
.
Note that, as a variant, in this case each part is labeled with its position in the partition.
The areas of the shadows of the three views are A066186(7) = 105, A194804(7) = 59 and A194805(7) = 25, therefore the total area of the three shadows is 105+59+25 = 189, so a(7) = 189.
A210991
Total area of the shadows of the three views of the shell model of partitions with n regions.
Original entry on oeis.org
0, 3, 9, 18, 21, 35, 39, 58, 61, 67, 71, 99, 103, 110, 115, 152, 155, 161, 165, 175, 181, 186, 238, 242, 249, 254, 265, 269, 277, 283, 352, 355, 361, 365, 375, 381, 386, 401, 406, 415, 422, 428, 522, 526, 533, 538, 549, 553, 561, 567, 584, 590, 595, 606
Offset: 0
For n = 11 the three views of the shell model of partitions with 11 regions look like this:
.
. A182181(11) = 35 A210692(11) = 29
.
. 1 1
. 1 1
. 1 1
. 1 1
. 1 1 1 1
. 1 1 1 1
. 1 1 1 1 1 1
. 2 1 1 1 1 2
. 2 1 1 1 1 1 1 2
. 3 2 2 2 1 1 1 1 2 2 3
. 6 3 4 2 5 3 4 2 3 2 1 1 2 3 4 5 6
. <------- Regions ------ ------------> N
. L
. a 1
. r * 2
. g * * 3
. e * 2
. s * * * 4
. t * * 3
. * * * * 5
. p * 2
. a * * * 4
. r * * 3
. t * * * * * 6
. s
.
. A182727(11) = 35
.
The areas of the shadows of the three views are A182181(11) = 35, A182727(11) = 35 and A210692(11) = 29, therefore the total area of the three shadows is 35+35+29 = 99, so a(11) = 99.
Since n = 11 is a partition number A000041 we can see that the rotated structure with 11 regions shows each row as a partition of 6 because A000041(6) = 11. See below:
.
. 6
. 3 3
. 4 2
. 2 2 2
. 5 1
. 3 2 1
. 4 1 1
. 2 2 1 1
. 3 1 1 1
. 2 1 1 1 1
. 1 1 1 1 1 1
.
Cf.
A000041,
A026905,
A135010,
A138121,
A141285,
A182703,
A194446,
A182181,
A182727,
A186114,
A206437,
A210692.
Original entry on oeis.org
1, 4, 7, 11, 16, 22, 29, 37, 46, 56, 67, 79, 92, 106, 121, 137, 154, 172, 191, 211, 232, 254, 277, 301, 326, 352, 379, 407, 436, 466, 497, 529, 562, 596, 631, 667, 704, 742, 781, 821, 862, 904, 947, 991, 1036, 1082, 1129, 1177, 1226, 1276, 1327, 1379, 1432
Offset: 1
a(4) = 11 = sum of row 4 terms of triangle A134868: (2, + 2 + 3 + 4).
a(4) = 11 = 1 + 10, where 10 = T(4).
a(4) = 11 = (1, 3, 3, 1) dot (1, 3, 0, 1) = (1 + 9 + 0 + 1).
-
a:=n->sum((stirling2(j+1,n)), j=1..n):seq(a(n), n=1..50); # Zerinvary Lajos, Apr 12 2008
-
Table[(n^2 + n)/2 + Boole[n != 1], {n, 53}] (* or *)
Table[PolygonalNumber@ n + Boole[n != 1], {n, 53}] (* Version 10.4, or *)
Table[Sum[StirlingS2[k + 1, n], {k, n}], {n, 53}] (* or *)
Rest@ CoefficientList[Series[x (1 + x - 2 x^2 + x^3)/(1 - x)^3, {x, 0, 53}], x] (* Michael De Vlieger, Jul 19 2016 *)
-
a(n)=if(n>1, n*(n+1)/2+1, 1) \\ Charles R Greathouse IV, Aug 05 2016
A206562
Triangle read by rows: T(n,k) = sum of all parts >= k in the last section of the set of partitions of n.
Original entry on oeis.org
1, 3, 2, 5, 3, 3, 11, 8, 4, 4, 15, 10, 8, 5, 5, 31, 24, 16, 10, 6, 6, 39, 28, 22, 16, 12, 7, 7, 71, 56, 40, 31, 19, 14, 8, 8, 94, 72, 58, 40, 32, 22, 16, 9, 9, 150, 120, 90, 72, 52, 37, 25, 18, 10, 10, 196, 154, 124, 94, 74, 54, 42, 28, 20, 11, 11
Offset: 1
Triangle begins:
1;
3, 2;
5, 3, 3;
11, 8, 4, 4;
15, 10, 8, 5, 5;
31, 24, 16, 10, 6, 6;
39, 28, 22, 16, 12, 7, 7;
71, 56, 40, 31, 19, 14, 8, 8;
94, 72, 58, 40, 32, 22, 16, 9, 9;
A207379
Triangle read by rows: T(n,k) = number of parts that are in the k-th column of the last section of the set of partitions of n.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 4, 4, 3, 2, 1, 1, 4, 4, 4, 3, 2, 1, 1, 7, 7, 6, 5, 3, 2, 1, 1, 8, 8, 8, 6, 5, 3, 2, 1, 1, 12, 12, 11, 10, 7, 5, 3, 2, 1, 1, 14, 14, 14, 12, 10, 7, 5, 3, 2, 1, 1, 21, 21, 20, 18, 14, 11, 7, 5, 3, 2, 1, 1
Offset: 1
Illustration of initial terms. First six rows of triangle as numbers of parts in the columns from the last sections of the first six natural numbers:
. 6
. 3 3
. 4 2
. 2 2 2
. 5 1
. 3 2 1
. 4 1 1
. 2 2 1 1
. 3 1 1 1
. 2 1 1 1 1
1 1 1 1 1 1
---------------------------------------------------
1, 1,1, 1,1,1, 2,2,1,1, 2,2,2,1,1, 4,4,3,2,1,1
...
Triangle begins:
1;
1, 1;
1, 1, 1;
2, 2, 1, 1;
2, 2, 2, 1, 1;
4, 4, 3, 2, 1, 1;
4, 4, 4, 3, 2, 1, 1;
7, 7, 6, 5, 3, 2, 1, 1;
8, 8, 8, 6, 5, 3, 2, 1, 1;
12, 12, 11, 10, 7, 5, 3, 2, 1, 1;
14, 14, 14, 12, 10, 7, 5, 3, 2, 1, 1;
21, 21, 20, 18, 14, 11, 7, 5, 3, 2, 1, 1;
A209655
Tetrahedron in which the n-th slice is also one of the three views of the shell model of partitions of A207380 with n shells.
Original entry on oeis.org
1, 2, 1, 1, 3, 2, 1, 1, 1, 1, 5, 4, 1, 2, 2, 1, 1, 2, 1, 1, 7, 6, 1, 4, 2, 1, 2, 3, 1, 1, 1, 2, 2, 1, 1
Offset: 1
--------------------------------------------------------
Illustration of first five
slices of the tetrahedron Row sum
--------------------------------------------------------
. 1, 1
. 2, 2
. 1, 1, 2
. 3, 3
. 2, 1, 3
. 1, 1, 1, 3
. 5, 5
. 4, 1, 5
. 2, 2, 1, 5
. 1, 2, 1, 1, 5
. 7, 7
. 6, 1, 7
. 4, 2, 1, 7
. 2, 3, 1, 1, 7
. 1, 2, 2, 1, 1, 7
--------------------------------------------------------
. 1, 3, 1, 6, 2, 1,12, 5, 2, 1,20, 8, 4, 2, 1,
.
Written as a triangle begins:
1;
2, 1, 1;
3, 2, 1, 1, 1, 1;
5, 4, 1, 2, 2, 1, 1, 2, 1, 1;
7, 6, 1, 4, 2, 1, 2, 3, 1, 1, 1, 2, 2, 1, 1;
In which row sums give A066186.
Cf.
A000041,
A000217,
A002260,
A004736,
A008284,
A026792,
A058398,
A058399,
A066186,
A135010,
A182703,
A182715,
A207380.
A210941
Triangle read by rows in which row n lists the parts > 1 of the n-th zone of the shell model of partitions, with a(1) = 1.
Original entry on oeis.org
1, 2, 3, 2, 2, 4, 3, 2, 5, 2, 2, 2, 4, 2, 3, 3, 6, 3, 2, 2, 5, 2, 4, 3, 7, 2, 2, 2, 2, 4, 2, 2, 3, 3, 2, 6, 2, 5, 3, 4, 4, 8, 3, 2, 2, 2, 5, 2, 2, 4, 3, 2, 7, 2, 3, 3, 3, 6, 3, 5, 4, 9, 2, 2, 2, 2, 2, 4, 2, 2, 2, 3, 3, 2, 2, 6, 2, 2, 5, 3, 2, 4, 4, 2, 8, 2
Offset: 1
Triangle First 15 zones of the
begins shell model of partitions
--------------------------------------------------
1; 1 1 1 1 1 1 1 1 1 1 1...
2; . 2 1 1 1 1 1 1 1 1 1...
3; . . 3 1 1 1 1 1 1 1 1...
2, 2; . 2 . 2 1 1 1 1 1 1 1...
4; . . . 4 1 1 1 1 1 1 1...
3, 2; . . 3 . 2 1 1 1 1 1 1...
5; . . . . 5 1 1 1 1 1 1...
2, 2, 2; . 2 . 2 . 2 1 1 1 1 1...
4, 2; . . . 4 . 2 1 1 1 1 1...
3, 3; . . 3 . . 3 1 1 1 1 1...
6; . . . . . 6 1 1 1 1 1...
3, 2, 2; . . 3 . 2 . 2 1 1 1 1...
5, 2; . . . . 5 . 2 1 1 1 1...
4, 3; . . . 4 . . 3 1 1 1 1...
7; . . . . . . 7 1 1 1 1...
-
a210941(n)={
my(p=[],r=[1]);
if(n>1,
my(c=2);
while(#r1]));
c++));
return(r[1..n])
} \\ Joe Slater, Sep 02 2024
Comments