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.

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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

Views

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

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

Views

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
Showing 1-2 of 2 results.