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 16 results. Next

A096322 Limiting sequence formed by rows of A094504 read backwards: rightmost floor(n/2)+1 terms of row n in table A094504.

Original entry on oeis.org

1, 3, 9, 25, 66, 165, 402, 943, 2163, 4835, 10598, 22785, 48215, 100470, 206620, 419662, 842928, 1675487, 3298688, 6436210, 12453352, 23905923, 45550529, 86180937, 161964145, 302447657
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Same sequence, multiplied by four, occurs in A096272.
a(n) is the number of solid partitions with layer structure an integer partition of (2n-2) in exactly (n-1) parts. - Wouter Meeussen, Mar 12 2025

Examples

			For n=3 the a(3)= 9 solid partitions are generated by the integer partitions of (2n-2) in exactly (n-1) parts with parts =1 and duplicate parts deleted, so just {3} and {2} :
 z[{{3}}], z[{{2,1}}], z[{{1,1,1}}], z[{{2},{1}}], z[{{1,1},{1}}], z[{{1},{1},{1}}] and  z[{{2}}], z[{{1,1}}], z[{{1},{1}}]
		

Crossrefs

Extensions

Extended to n=26, Wouter Meeussen, May 23 2025

A096272 Triangle read by rows: T(n,k) counts solid partitions of n such that the maximum of planes, rows, columns and values is k.

Original entry on oeis.org

1, 0, 4, 0, 6, 4, 0, 10, 12, 4, 0, 13, 30, 12, 4, 0, 18, 70, 36, 12, 4, 0, 19, 142, 94, 36, 12, 4, 0, 24, 274, 234, 100, 36, 12, 4, 0, 19, 501, 534, 258, 100, 36, 12, 4, 0, 18, 872, 1186, 630, 264, 100, 36, 12, 4, 0, 13, 1449, 2486, 1482, 654, 264, 100, 36, 12, 4, 0, 10, 2336, 5080, 3346, 1578, 660, 264, 100, 36, 12, 4
Offset: 1

Views

Author

Wouter Meeussen, Jun 22 2004, Sep 21 2008

Keywords

Comments

Solid partitions of n that fit inside a 4-dimensional k X k X k X k box. Regard solid partitions as safe pilings of boxes in a corner, stacking height does not increase away from the corner and each box contains an integer and this integer too does not increase away from the corner.
If k > 1+(n/2) then T(n,k) = T(n-1,k-1). For large n and k, each row ends as the reverse of 4, 12, 36, 100, 264, 660, 1608, 3772, 8652, 19340, 42392, 91140, 192860, 401880, 836480, ... = 4*A096322(i), i>=1.

Examples

			Triangle T(n,k) begins:
  1;
  0,  4;
  0,  6,  4;
  0, 10, 12,  4;
  0, 13, 30, 12,  4;
  0, 18, 70, 36, 12, 4;
  ...
T(16,2) = 1 because only { {{2,2},{2,2}}, {{2,2},{2,2}} } has only two planes, each plane has no more than 2 columns, each column no more than 2 rows and each element is no larger than 2.
		

Crossrefs

Programs

  • Mathematica
    Table[Count[Max[Max@(Flatten@(List@@#)),Max@@Map[Length,#,{-2}],Length/@List@@#,Length[#]]&/@Flatten[solidformBTK/@IntegerPartitions[n]] ,#]&/@Range[n],{n,1,12}]; (* see link for function definition *)

A096573 Number of fixed points of mirroring operation on solid partitions.

Original entry on oeis.org

1, 2, 4, 8, 13, 24, 39, 68, 110, 182, 288, 468, 728, 1150, 1770, 2751, 4175, 6388, 9597, 14495, 21571, 32200, 47498
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Uses function "solidformBTK" from link below.

Examples

			Solid partition [{{3, 1, 1, 1}, {3}}, {{2, 1}}, {{1}}, {{1}}, {{1}}] mirrors into [{{3, 3}, {1}, {1}, {1}}, {{2}, {1}}, {{1}}, {{1}}, {{1}}] by mirroring each layer as a plane partition.
		

Crossrefs

Programs

  • Mathematica
    Tr/@Table[Count[solidformBTK[par],arg_z/;flip[arg]==arg],{n,20},{par,IntegerPartitions[n]}] (* Wouter Meeussen, Feb 05 2025  *)

Extensions

a(16)-a(23) from Wouter Meeussen, Feb 05 2025

A096574 Number of asymmetric solid partitions under mirroring operation.

Original entry on oeis.org

0, 1, 3, 9, 23, 58, 134, 308, 677, 1470, 3106, 6479, 13260, 26827, 53516
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Uses function "solidformBTK" from link above.

Examples

			Solid partition [{{3, 1, 1, 1}, {3}}, {{2, 1}}, {{1}}, {{1}}, {{1}}] mirrors into [{{3, 3}, {1}, {1}, {1}}, {{2}, {1}}, {{1}}, {{1}}, {{1}}] by mirroring each layer as a plane partition.
		

Crossrefs

Formula

a(n) = (A000293(n) - A096573(n))/2.

A096575 Number of fixed points of solid partitions under rotation operation.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 4, 6, 6, 8, 11, 13, 17, 24, 28, 36, 47, 56, 69, 94, 114, 138, 177, 218, 262
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Rotation has permutation cycle length 1 or 3. Uses function "solidformBTK" from link below.
Is this the same sequence as A002722? - R. J. Mathar, Sep 04 2008 [This still seems to be true even after 20 terms. - N. J. A. Sloane, Feb 05 2025]
Rotation of each of the plane partitions in a solid partition appears to lead to the same count of fixed points as rotating the 3D-partition as a whole. - Wouter Meeussen, Feb 05 2025

Examples

			Solid partition [{{3, 1, 1, 1}, {3}}, {{2, 1}}, {{1}}, {{1}}, {{1}}] rotates into [{{4, 1}, {1, 1}, {1, 1}}, {{2}, {1}}, {{1}}, {{1}}, {{1}}] by rotating each layer as a plane partition.
		

Crossrefs

Programs

  • Mathematica
    Tr/@Table[Count[solidformBTK[par], arg_z /;turn[arg]==arg],{n,20}, {par, IntegerPartitions[n]}]

Extensions

a(16)-a(23) from Wouter Meeussen, Feb 05 2025
a(24)-a(25) from Wouter Meeussen, Jul 27 2025

A096577 Number of fixed points of solid partitions under 'time-lapse' operation.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 1, 0, 2, 0, 2, 0, 2, 0, 4, 1, 5, 0, 7, 1, 7, 0, 14
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Operation 'time lapse', or 'lapse', L, operates on a solid partition by creating a new one, layer by layer. Layer k is defined by its 3-dimensional-Ferrers plot, equal to the (existence of) elements of the solid partition with value >= k. As if taking a time-lapse picture of the solid partition, filtering out elements less than k and projecting the resulting structure (filled with ones) to the base plane. Given there are three planes to project into, together with the starting solid partition, that makes four 'isomers'.

Examples

			Solid partition [{{3,1,1,1},{3}},{{2,1}},{{1}},{{1}},{{1}}] lapses (L) into
[{{4,1},{2},{1},{1},{1}},{{1,1},{1}},{{1,1}}], then into
[{{2,1,1,1,1},{2,1},{2}},{{1,1}},{{1}},{{1}}], further into
[{{5,2,1},{2},{1},{1}},{{1,1,1}}] and returns after L^4 to
[{{3,1,1,1},{3}},{{2,1}},{{1}},{{1}},{{1}}].
		

Crossrefs

Programs

  • Mathematica
    (* See link above. *)
    Tr/@Table[Count[solidformBTK[par],arg_z/;lapse[arg]==arg],{n,20},{par,IntegerPartitions[n]}] (* Wouter Meeussen, Feb 05 2025 *)

Extensions

a(16)-a(23) from Wouter Meeussen, Mar 19 2025

A096576 Number of solid partitions asymmetric under rotation operation.

Original entry on oeis.org

0, 1, 3, 8, 19, 46, 101, 226, 486, 1038, 2163, 4471, 9077, 18260, 36258
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Rotation has permutation cycle length 1 or 3. Uses function "solidformBTK" from link above.

Examples

			Solid partition [{{3, 1, 1, 1}, {3}}, {{2, 1}}, {{1}}, {{1}}, {{1}}] rotates into [{{4, 1}, {1, 1}, {1, 1}}, {{2}, {1}}, {{1}}, {{1}}, {{1}}] by rotating each layer as a plane partition.
		

Crossrefs

Programs

Formula

a(n) = (A000293(n) - A096575(n))/3.

A096578 Number of solid partitions with period (cycle length) two under 'time-lapse' operation.

Original entry on oeis.org

0, 0, 1, 1, 1, 2, 3, 6, 7, 11, 15, 25, 33, 48, 65
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Comments

Operation 'time lapse', or 'lapse', L, operates on a solid partition by creating a new one, layer by layer. Layer k is defined by its 3-dimensional-Ferrers plot, equal to the (existence of) elements of the solid partition with value >= k. As if taking a time-lapse picture of the solid partition, filtering out elements less than k and projecting the resulting structure (filled with ones) to the base plane. Given there are three plane to project into, together with the starting solid partition, that makezs four 'isomers'.

Examples

			Solid partition [{{3,1,1,1},{3}},{{2,1}},{{1}},{{1}},{{1}}] lapses (L) into
[{{4,1},{2},{1},{1},{1}},{{1,1},{1}},{{1,1}}], then into
[{{2,1,1,1,1},{2,1},{2}},{{1,1}},{{1}},{{1}}], further into
[{{5,2,1},{2},{1},{1}},{{1,1,1}}] and returns after L^4 to
[{{3,1,1,1},{3}},{{2,1}},{{1}},{{1}},{{1}}]
		

Crossrefs

Programs

  • Mathematica
    (* See link above. *)

A096581 Number of solid partitions non-symmetric under L^2 (L= 'time-lapse' symmetry operation) on solid partitions.

Original entry on oeis.org

0, 2, 4, 12, 28, 68, 150, 336, 724, 1550, 3234, 6688, 13590, 27354, 54334
Offset: 1

Views

Author

Wouter Meeussen, Jun 27 2004

Keywords

Examples

			Solid partition [{{3,1,1,1},{3}},{{2,1}},{{1}},{{1}},{{1}}] lapses (L) into
[{{4,1},{2},{1},{1},{1}},{{1,1},{1}},{{1,1}}], then into
[{{2,1,1,1,1},{2,1},{2}},{{1,1}},{{1}},{{1}}], further into
[{{5,2,1},{2},{1},{1}},{{1,1,1}}] and returns after L^4 to
[{{3,1,1,1},{3}},{{2,1}},{{1}},{{1}},{{1}}]
		

Crossrefs

Programs

  • Mathematica
    (* See link above. *)

Formula

By definition, A000293(n) = A096580(n) + 2*a(n).

A089924 Number of plane partitions of n with 3 or more columns.

Original entry on oeis.org

0, 0, 1, 3, 8, 19, 41, 85, 167, 319, 588, 1066, 1880, 3272, 5588, 9431, 15686, 25841, 42070, 67926, 108634, 172467, 271643, 425109, 660756, 1021170, 1568905, 2398059, 3646437, 5519025, 8314623, 12473538, 18634748, 27731820, 41113453, 60735830, 89411503, 131193675
Offset: 1

Views

Author

Wouter Meeussen, Jan 11 2004

Keywords

Comments

Because of symmetry of the 3-dimensional-Ferrers plots, this sequence also counts the plane partitions with 3 or more rows and the plane partitions with maximal element >= 3

Examples

			a(4)=3:
  1111 111 211
  .... 1.. ...
		

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, add(add(min(d, k)
          *d, d=numtheory[divisors](j))*b(n-j, k), j=1..n)/n)
        end:
    a:= n-> b(n, infinity)-b(n,2):
    seq(a(n), n=1..50);  # Alois P. Heinz, Sep 24 2018
  • Mathematica
    (* planepartitions[] : see link *); Table[Count[planepartitions[n], q_ /; Length[First[q]] >= 3], {n, 12}]

Extensions

a(21)-a(27) from Vaclav Kotesovec, May 05 2018
a(28)-a(38) from Alois P. Heinz, Sep 24 2018
Showing 1-10 of 16 results. Next