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.

User: Aidan Markey

Aidan Markey's wiki page.

Aidan Markey has authored 4 sequences.

A387259 Number of unordered pairs of partitions of n with the same number of parts.

Original entry on oeis.org

1, 1, 2, 3, 6, 9, 18, 28, 52, 86, 151, 246, 431, 694, 1167, 1884, 3095, 4904, 7919, 12379, 19596, 30315, 47117, 71922, 110332, 166403, 251547, 375575, 560787, 828276, 1223544, 1789656, 2616001, 3793295, 5491711, 7895309, 11333811, 16164595, 23013551, 32584816
Offset: 0

Author

Aidan Markey, Aug 24 2025

Keywords

Comments

The corresponding sequence for ordered pairs of partitions is A238312.

Examples

			For example, a(4)=6: (4,4) (3+1,3+1) (3+1,2+2) (2+2,2+2) (2+1+1,2+1+1) (1+1+1+1,1+1+1+1).
Note that (3+1,2+2) and (2+2,3+1) are not both counted.
		

Crossrefs

Formula

a(n) = Sum_{k=0..n} A000217(A072233(n,k)).
a(n) = A380126(n) - A380124(n).

A380126 Total number of ways of partitioning n and any natural number less than or equal to n into the same number of parts, not treating partitions of n and itself in a different order as distinct.

Original entry on oeis.org

1, 1, 3, 6, 14, 26, 58, 106, 214, 394, 742, 1314, 2406, 4139, 7234, 12250, 20778, 34279, 56805, 91866, 148816, 236772, 375899, 588208, 919235, 1417538, 2180608, 3320197, 5038918, 7577850, 11363516, 16899942, 25056925, 36892553, 54136934, 78951553, 114783293, 165922204
Offset: 0

Author

Aidan Markey, Jan 12 2025

Keywords

Examples

			For example, a(4)=14:
  4 and 1: (4,1),
  4 and 2: (4,2) (3+1,1+1) (2+2,1+1),
  4 and 3: (4,3) (3+1,2+1) (2+2,2+1) (2+1+1,1+1+1),
  4 and 4: (4,4) (3+1,3+1) (3+1,2+2) (2+2,2+2) (2+1+1,2+1+1) (1+1+1+1,1+1+1+1).
Note that (3+1,2+2) and (2+2,3+1) are not both counted.
		

Crossrefs

Similar to A380124, A380125.

Formula

a(n) = Sum_{i=0..n-1} Sum_{j=0..i} p(n,j)*p(i,j) + Sum_{j=0..n} (p(n,j)*(p(n,j)+1))/2, where p(n,j) is the number of partitions of n into j positive parts (A008284, A072233).

Extensions

More terms from Chai Wah Wu, Feb 19 2025
a(0)=1 prepended by Alois P. Heinz, Aug 24 2025

A380125 Total number of ways of partitioning n and any natural number less than or equal to n into the same number of parts, treating partitions of n and itself in a different order as distinct.

Original entry on oeis.org

1, 1, 3, 6, 15, 28, 65, 119, 244, 450, 851, 1504, 2760, 4732, 8266, 13958, 23642, 38886, 64339, 103755, 167785, 266295, 422014, 658875, 1027992, 1581983, 2429719, 3692762, 5595987, 8401561, 12581456, 18682756, 27664577, 40675705, 59616335, 86831979, 126099127, 182065162
Offset: 0

Author

Aidan Markey, Jan 12 2025

Keywords

Examples

			For example, a(4)=15:
  4 and 1: (4,1),
  4 and 2: (4,2) (3+1,1+1) (2+2,1+1),
  4 and 3: (4,3) (3+1,2+1) (2+2,2+1) (2+1+1,1+1+1),
  4 and 4: (4,4) (3+1,3+1) (3+1,2+2) (2+2,3+1) (2+2,2+2) (2+1+1,2+1+1) (1+1+1+1,1+1+1+1).
Note that (3+1,2+2) and (2+2,3+1) are both counted.
		

Crossrefs

Similar to A380124, A380126.

Formula

a(n) = Sum_{i=0..n} Sum_{j=0..i} p(n,j)*p(i,j), where p(n,j) is the number of partitions of n into j positive parts (A008284, A072233).
a(n) = A380124(n) + A238312(n).

Extensions

More terms from Chai Wah Wu, Feb 19 2025
a(0)=1 prepended by Alois P. Heinz, Aug 24 2025

A380124 Total number of ways of partitioning n and any natural number less than n into the same number of parts.

Original entry on oeis.org

0, 0, 1, 3, 8, 17, 40, 78, 162, 308, 591, 1068, 1975, 3445, 6067, 10366, 17683, 29375, 48886, 79487, 129220, 206457, 328782, 516286, 808903, 1251135, 1929061, 2944622, 4478131, 6749574, 10139972, 15110286, 22440924, 33099258, 48645223, 71056244, 103449482, 149757609
Offset: 0

Author

Aidan Markey, Jan 12 2025

Keywords

Examples

			For example, a(4)=8:
  4 and 1: (4,1),
  4 and 2: (4,2) (3+1,1+1) (2+2,1+1),
  4 and 3: (4,3) (3+1,2+1) (2+2,2+1) (2+1+1,1+1+1).
		

Crossrefs

Similar to A380125, A380126.

Formula

a(n) = Sum_{i=1..n-1} Sum_{j=1..i} p(n,j)*p(i,j), where p(n,j) is the number of partitions of n into j positive parts (A008284, A072233).

Extensions

More terms from Chai Wah Wu, Feb 19 2025