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.

Showing 1-10 of 11 results. Next

A138533 Resort the multinomial sequence A036038 by source partition as described in A126442, A129306 and A136101.

Original entry on oeis.org

1, 2, 1, 6, 3, 1, 24, 12, 4, 1, 6, 120, 60, 20, 5, 1, 30, 10, 720, 360, 120, 30, 6, 1, 180, 60, 15, 20, 90
Offset: 1

Views

Author

Alford Arnold, Mar 27 2008

Keywords

Comments

Multinomials count permutations of multisets and also paths in lattices; for example, there are six paths (from null to full) through the lattice of divisors for signature 36: 2233 2323 2332 3223 3232 and 3322.

Examples

			a(11) is six because the eleventh least prime signature in source format is 36 the signature for partition 2+2 the ninth partition and A036038(9) = 6.
The tables begin:
1.......2.......6.......24......120.....720....5040.....40320......362880
........1.......3.......12.......60.....360....2520.....20160......181440
................1.......4........20.....120.....840......6720.......60480
........................1........5.......30.....210......1680.......15120
.. ..............................1........6......42......336........3024
..........................................1.......7.......56.........504
..................................................1........8..........72
...........................................................1...........9
.......................................................................1
........................6........30.....180....1260....10080........90720
.................................10......60.....420.....3360........30240
...
		

Crossrefs

Cf. A173333. [From Reinhard Zumkeller, Feb 19 2010]

A131420 A tabular sequence of arrays counting ordered factorizations over least prime signatures. The unordered version is described by sequence A129306.

Original entry on oeis.org

1, 2, 3, 4, 8, 13, 8, 20, 44, 75, 26, 16, 48, 132, 308, 541, 76, 176, 32, 112, 368, 1076, 2612, 4683, 208, 604, 1460, 252, 818, 64, 256, 876, 3408, 10404, 25988, 47293, 544, 1888, 5740, 14300, 768, 2316, 3172, 7880, 128, 576, 2496, 10096, 36848, 116180
Offset: 1

Views

Author

Alford Arnold, Jul 10 2007

Keywords

Comments

The display has 1 2 3 5 7 11 15 ... terms per column. (cf. A000041)
The arrays begin
1.....2.....4......8......16.....32.....64......128
......3.....8.....20......48....112....256......576
...........13.....44.....132....368....976.....2496
..................75.....308...1076...3408....10096
.........................541...2612..10404....36848
...............................4683..25988...116180
.....................................47293...296564
.............................................545835
..................26......76....208....544
.........................176....604...1888
...............................1460...5740
.....................................14300
................................252....768
......................................2316
................................818...3172
......................................7880
with column sums
1....5....25....173....1297....12225....124997 => A035341
Column i corresponds to partitions of i. The rows correspond successively to the partitions {i}, {i-1,1},{i-2,1,1},{i-3,1,1,1}, ..., {i-7,1,1,1,1,1,1,1}, {i-2,2}, {i-3,2,1}, {i-4,2,1,1}, {i-5,2,1,1,1}, {i-3,3}, {i-3,3,1}, {i-4,2,2}, {i-5,2,2,1}. - Roger Lipsett, Feb 26 2016

Examples

			36 = 2*2*3*3 and is in A025487. There are 26 ways to factor 36 so a(11) = 26.
		

Crossrefs

Programs

  • Mathematica
    gozinta counts ordered factorizations of an integer, and if lst is a partition we have
    gozinta[1] = 1;
    gozinta[n_] := gozinta[n] = 1 + Sum[gozinta[n/i], {i, Rest@Most@Divisors@n}]
    a[lst_] := gozinta[Times @@ (Array[Prime, Length@lst]^lst)] (* Roger Lipsett, Feb 26 2016 *)

Extensions

Corrected entries in table in comments section - Roger Lipsett, Feb 26 2016

A346426 Number A(n,k) of partitions of the (n+k)-multiset {0,...,0,1,2,...,k} with n 0's; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 5, 5, 4, 3, 15, 15, 11, 7, 5, 52, 52, 36, 21, 12, 7, 203, 203, 135, 74, 38, 19, 11, 877, 877, 566, 296, 141, 64, 30, 15, 4140, 4140, 2610, 1315, 592, 250, 105, 45, 22, 21147, 21147, 13082, 6393, 2752, 1098, 426, 165, 67, 30, 115975, 115975, 70631, 33645, 13960, 5317, 1940, 696, 254, 97, 42
Offset: 0

Views

Author

Alois P. Heinz, Jul 16 2021

Keywords

Comments

Also number A(n,k) of factorizations of 2^n * Product_{i=1..k} prime(i+1); A(3,1) = 7: 2*2*2*3, 2*3*4, 4*6, 2*2*6, 3*8, 2*12, 24; A(1,2) = 5: 2*3*5, 5*6, 3*10, 2*15, 30.

Examples

			A(2,2) = 11: 00|1|2, 001|2, 1|002, 0|0|1|2, 0|01|2, 0|1|02, 01|02, 00|12, 0|0|12, 0|012, 0012.
Square array A(n,k) begins:
   1,  1,   2,    5,   15,    52,    203,     877,    4140, ...
   1,  2,   5,   15,   52,   203,    877,    4140,   21147, ...
   2,  4,  11,   36,  135,   566,   2610,   13082,   70631, ...
   3,  7,  21,   74,  296,  1315,   6393,   33645,  190085, ...
   5, 12,  38,  141,  592,  2752,  13960,   76464,  448603, ...
   7, 19,  64,  250, 1098,  5317,  28009,  158926,  963913, ...
  11, 30, 105,  426, 1940,  9722,  52902,  309546, 1933171, ...
  15, 45, 165,  696, 3281, 16972,  95129,  572402, 3670878, ...
  22, 67, 254, 1106, 5372, 28582, 164528, 1015356, 6670707, ...
  ...
		

Crossrefs

Programs

  • Maple
    s:= proc(n) option remember; expand(`if`(n=0, 1,
          x*add(s(n-j)*binomial(n-1, j-1), j=1..n)))
        end:
    S:= proc(n, k) option remember; coeff(s(n), x, k) end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i=0,
          combinat[numbpart](n), add(b(n-j, i-1), j=0..n)))
        end:
    A:= (n, k)-> add(S(k, j)*b(n, j), j=0..k):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    s[n_] := s[n] = Expand[If[n == 0, 1, x Sum[s[n - j] Binomial[n - 1, j - 1], {j, 1, n}]]];
    S[n_, k_] := S[n, k] = Coefficient[s[n], x, k];
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i == 0, PartitionsP[n], Sum[b[n - j, i - 1], {j, 0, n}]]];
    A[n_, k_] := Sum[S[k, j] b[n, j], {j, 0, k}];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Aug 18 2021, after Alois P. Heinz *)

Formula

A(n,k) = A001055(A000079(n)*A070826(k+1)).
A(n,k) = Sum_{j=0..k} A048993(k,j)*A292508(n,j+1).
A(n,k) = Sum_{j=0..k} Stirling2(k,j)*Sum_{i=0..n} binomial(j+i-1,i)*A000041(n-i).

A126442 Triangular array t read by rows: t(0,k) is p(k), the number of partitions of the k-multiset {0,0,...,0} with k zeros. For 0 <= n < k, t(n, k) is the number of partitions of the k-multiset {0, 0, ..., 0, 1, 2, 3, ..., k-n} with n zeros.

Original entry on oeis.org

1, 2, 2, 3, 4, 5, 5, 7, 11, 15, 7, 12, 21, 36, 52, 11, 19, 38, 74, 135, 203, 15, 30, 64, 141, 296, 566, 877, 22, 45, 105, 250, 592, 1315, 2610, 4140, 30, 67, 165, 426, 1098, 2752, 6393, 13082, 21147, 42, 97, 254, 696, 1940, 5317, 13960, 33645, 70631, 115975
Offset: 1

Views

Author

Alford Arnold, Jan 28 2007

Keywords

Comments

First in a series of triangular arrays which comprise subsequences of A096443(n).
The second array begins 9 16 26 29 52 92 47 98 198 371 and when the arrays are aligned as illustrated in triangle A126441 with p(n) values they sum to A035310 which counts unordered multisets.
Let t(n, k) be the number of ways to partition the k-multiset {0,0,...,0,1,2,3,4,...,k-n} with n zeros, 0 <= n < k. Then t(n, k) = sum_i = 0..k j = 0..n S(n, j) C(i, j) p(k - n - i), where S(n, j) are Stirling numbers of the second kind, C(i, j) are the number of compositions of i distinct objects into j parts, and p is the integer partition function.
To see this, partition [n] into j blocks; there are S(n, j) partitions. For such a partition x and for each i, there are C(i, j) ways to distribute i zeros into x, because the blocks of x are all distinct. There are p(k-n-i) ways to partition the remaining k-n-i zeros. Multiplying and summing gives the result. - George Beck, Jan 10 2011
Values are also part of A096443, A129306 and A249620. Columns are also columns of the last one of these irregular triangles. See "Partitions_of_multisets" link. - Tilman Piesk, Nov 09 2014

Examples

			This first array includes only the hook cases. A096443(9,14,16) correspond to partitions [2,2], [3,2] and [2,2,1] so these values do not appear in A126442.
The array begins:
1
2 2
3 4 5
5 7 11 15
7 12 21 36 52
		

Crossrefs

Programs

  • Mathematica
    (* The triangle is flattened to a sequence. *)
    t[n_, k_] := Sum[StirlingS2[n, j] * Binomial[-1 + i + j, i] * PartitionsP[k - n - i], {j, 0, n}, {i, 0, k - n}]; Table[ t[n, k], {k, 10}, {n, 0, k - 1}] // Flatten (* George Beck, Jan 10 2011 *)

Extensions

Definition clarified by George Beck, Jan 11 2011

A249620 Triangle read by rows: T(m,n) = number of partitions of the multiset with m elements and signature corresponding to n-th integer partition (A194602).

Original entry on oeis.org

1, 1, 2, 2, 5, 4, 3, 15, 11, 7, 9, 5, 52, 36, 21, 26, 12, 16, 7, 203, 135, 74, 92, 38, 52, 19, 66, 29, 31, 11, 877, 566, 296, 371, 141, 198, 64, 249, 98, 109, 30, 137, 47, 57, 15, 4140, 2610, 1315, 1663, 592, 850, 250, 1075, 392, 444, 105, 560
Offset: 0

Views

Author

Tilman Piesk, Nov 04 2014

Keywords

Comments

This triangle shows the same numbers in each row as A129306 and A096443, but in this arrangement the multisets in column n correspond to the n-th integer partition in the infinite order defined by A194602.
Row lengths: A000041 (partition numbers), Row sums: A035310
Columns: 0: A000110 (Bell), 1: A035098 (near-Bell), 2: A169587, 4: A169588
Last in row: end-1: A091437, end: A000041 (partition numbers)
The rightmost columns form a reflected version of the triangle A126442:
n 0 1 2 4 6 10 14 21 (A000041(1,2,3...)-1)
m
1 1
2 2 2
3 5 4 3
4 15 11 7 5
5 52 36 21 12 7
6 203 135 74 38 19 11
7 877 566 296 141 64 30 15
8 4140 2610 1315 592 250 105 45 22
A249619 shows the number of permutations of the same multisets.

Examples

			See "The T(5,2)=21 partitions of {1,1,1,2,3}" link. Similar links for m=1..8 are in "Partitions of multisets" (Wikiversity).
Triangle begins:
  n     0    1   2   3   4   5   6   7   8   9  10
m
0       1
1       1
2       2    2
3       5    4   3
4      15   11   7   9   5
5      52   36  21  26  12  16   7
6     203  135  74  92  38  52  19  66  29  31  11
		

Crossrefs

A093802 Number of distinct factorizations of 105*2^n.

Original entry on oeis.org

5, 15, 36, 74, 141, 250, 426, 696, 1106, 1711, 2593, 3852, 5635, 8118, 11548, 16231, 22577, 31092, 42447, 57464, 77213, 103009, 136529, 179830, 235514, 306751, 397506, 512607, 658030, 841020, 1070490, 1357195, 1714274, 2157539, 2706174, 3383187, 4216358
Offset: 0

Views

Author

Alford Arnold, May 19 2004

Keywords

Examples

			105*A000079 is 105, 210, 420, 840, 1680, 3360, ... and there are 15 distinct factorizations of 210 so a(1) = 15.
a(0) = 5: 105*2^0 = 105 = 3*5*7 = 3*35 = 5*21 = 7*15. - _Alois P. Heinz_, May 26 2013
		

Crossrefs

Similar sequences: 45*A000079 => A002763, [1, 3, 9, 27, 81, 243...]*A000079 => A054225, 1*A002110 => A000110, 2*A002110 => A035098, A000142 => A076716.
Column k=3 of A346426.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember;
          `if`(n>k, 0, 1) +`if`(isprime(n), 0,
          add(`if`(d>k, 0, b(n/d, d)), d=divisors(n) minus {1, n}))
        end:
    a:= n-> b((105*2^n)$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, May 26 2013
  • Mathematica
    b[n_, k_] := b[n, k] = If[n > k, 0, 1] + If[PrimeQ[n], 0,
         Sum[If[d > k, 0, b[n/d, d]], {d, Divisors[n][[2;;-2]]}]];
    a[n_] := b[105*2^n, 105*2^n];
    Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Jul 15 2021, after Alois P. Heinz *)

Extensions

2 more terms from Alford Arnold, Aug 29 2007
Corrected offset and extended beyond a(7) by Alois P. Heinz, May 26 2013

A002763 Number of bipartite partitions.

Original entry on oeis.org

4, 11, 26, 52, 98, 171, 289, 467, 737, 1131, 1704, 2515, 3661, 5246, 7430, 10396, 14405, 19760, 26884, 36269, 48583, 64614, 85399, 112170, 146526, 190362, 246099, 316621, 405556, 517224, 657012, 831320, 1048055, 1316611, 1648486, 2057324, 2559719, 3175309
Offset: 0

Views

Author

Keywords

References

  • M. S. Cheema and H. Gupta, Tables of Partitions of Gaussian Integers. National Institute of Sciences of India, Mathematical Tables, Vol. 1, New Delhi, 1956, p. 11.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember;
          `if`(n>k, 0, 1) +`if`(isprime(n), 0,
          add(`if`(d>k, 0, b(n/d, d)), d=divisors(n) minus {1, n}))
        end:
    a:= n-> b((45*2^n)$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, May 26 2013
  • Mathematica
    b[n_, k_] := b[n, k] = If[n>k, 0, 1] + If[PrimeQ[n], 0, Sum[If[d>k, 0, b[n/d, d]], {d, DeleteCases[Divisors[n], 1|n]}]]; a[n_] := b[45*2^n, 45*2^n]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Mar 20 2014, after Alois P. Heinz *)
    nmax = 100; CoefficientList[Series[(4 - x - 3*x^2 + x^3) / ((1 - x)^3 * (1 + x)) / Product[1 - x^k, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 07 2017 *)

Formula

a(n) = a(n-1) + A000041(n) + A000070(n) + A000291(n), for n>0 - Alford Arnold, Dec 10 2007
From Vaclav Kotesovec, Jan 07 2017: (Start)
G.f.: (4 - x - 3*x^2 + x^3) / ((1-x)^3 * (1+x)) * Product_{k>=1} 1/(1-x^k).
a(n) ~ exp(Pi*sqrt(2*n/3)) * 3*sqrt(n)/(2*sqrt(2)*Pi^3).
(End)

Extensions

Extended beyond a(25) by Alois P. Heinz, May 26 2013

A136101 Resort sequence A025487 by source partition as described by A053445 and A126442.

Original entry on oeis.org

1, 2, 4, 6, 8, 12, 30, 16, 24, 60, 210, 36, 32, 48, 120, 420, 2310, 72, 180, 64, 96, 240, 840, 4620, 30030, 144, 360, 1260, 216, 900, 128, 192, 480, 1680, 9240, 60060, 510510, 288, 720, 2520, 13860, 432, 1080, 1800, 6300, 256, 384, 960, 3360, 18480, 120120
Offset: 0

Views

Author

Alford Arnold, Jan 01 2008

Keywords

Examples

			Let a(0) = 1 then let the irregular table begin:
2....4....8....16....32....64....
....6...12....24....48....96....
........30....60...120...240....
.............210...420...840....
..................2310..4620....
.......................30030....
..............36....72...144....
...................180...360....
........................1260....
.........................216....
.........................900....
		

Crossrefs

A131419 Central diagonal and left half of table A054225 which counts the partitions of n objects of 2 colors.

Original entry on oeis.org

1, 1, 2, 2, 3, 4, 5, 7, 9, 7, 12, 16, 11, 19, 29, 31, 15, 30, 47, 57, 22, 45, 77, 97, 109, 30, 67, 118, 162, 189, 42, 97, 181, 257, 323, 339, 56, 139, 267, 401, 522, 589, 77, 195, 392, 608, 831, 975, 1043, 101, 272, 560, 907, 1279, 1576, 1752, 135, 373
Offset: 0

Views

Author

Alford Arnold, Jul 11 2007

Keywords

Comments

Every diagonal appears in sequence A129306.

Examples

			Table A054225 begins
1
1...1
2...2...2
3...4...4...3
5...7...9...7...5
7..12..16..16..12..7
The diagonals in the new table begin
1..1..2..3..5...7...11...15...22...30..42 A000041
.....2..4..7..12...19...30...45...67..97 A000070
........9.16..29...47...77..118..181
..........31..57...97..162..257
.............109..189..323
..................339
		

Crossrefs

Extensions

More terms from R. J. Mathar, Sep 02 2007

A131888 Follow each least prime signature by the corresponding value in the array A096443.

Original entry on oeis.org

1, 1, 2, 1, 4, 2, 6, 2, 8, 3, 12, 4, 30, 5, 16, 5, 24, 7, 36, 9, 60, 11, 210, 15, 32, 7, 48, 12, 72, 16, 120, 21, 180, 26, 420, 36, 2310, 52, 64, 11, 96, 19, 144, 29, 240, 38, 216, 31, 360, 52, 840, 74, 900, 66, 1260, 92, 4620, 135, 30030, 203
Offset: 0

Views

Author

Alford Arnold, Jul 23 2007

Keywords

Examples

			Array A096443 begins
1..1..2..3...5...7..11..15...22...30
.....2..4...7..12..19..30...45...67
............9..16..29..47...77..118
........5..11..21..38..64..105..165
etc
so the sequence begins 1 1 2 1 4 2 6 2 8 3 12 4 30 5 ...
		

Crossrefs

Showing 1-10 of 11 results. Next