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 1-3 of 3 results.

A161923 Numbers n with property that each number corresponds to one of the partitions described in sequence A160643 and counted in A161921.

Original entry on oeis.org

28, 52, 58, 100, 106, 118, 112, 116, 124, 196, 202, 214, 238, 208, 212, 220, 226, 234, 250, 388, 394, 406, 430, 478, 232, 244, 400, 404, 412, 418, 426, 442, 454, 470, 502, 772, 778, 790, 814, 862, 958
Offset: 1

Views

Author

Alford Arnold, Jul 05 2009

Keywords

Examples

			The numbers form an irregular table with shape A161921 as follows:
28
52 58
100 106 118
112 116 124 196 202 214 238
208 212 220 226 234 250 388 394 406 430 478
		

Crossrefs

A125106 (Describes the mapping to partitions)

A160644 First of two sequences bisecting the second differences of the partition numbers (see A053445).

Original entry on oeis.org

1, 1, 2, 3, 4, 7, 10, 14, 22, 32, 45, 67, 95, 134, 192, 269, 373, 521, 718, 983, 1346, 1827, 2465, 3323, 4449, 5929, 7882, 10426, 13735, 18047, 23613, 30788, 40034, 51877, 67013, 86341, 110905, 142063, 181529, 231340, 294077, 372977, 471908, 595725, 750432
Offset: 1

Views

Author

Alford Arnold, May 21 2009

Keywords

Comments

A160644 also counts selected unrestricted partition having an EVEN total and with minimum part two. For example it counts these three partitions of eight: 4+4, 3+3+2, and 2+2+2+2.

Examples

			A053445 begins
1 0 1 0 2 0 3 1 4 2 7 3 10 7 14 11 22 17 32 28 45 ...
therefore a(n) begins
1 1 2 3 4 7 10 14 22 32 45 67 95 134 192 ...
		

Crossrefs

Cf. A000041, A002685, A053445, A160643, A161921 (the other bisection).

Programs

  • Mathematica
    Take[Differences[PartitionsP[Range[0,100]],2],{1,-1,2}] (* Harvey P. Dale, Aug 05 2019 *)

A160643 Bisect A053445 then calculate the first differences of the resulting sequence.

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 4, 4, 6, 11, 15, 20, 33, 43, 60, 88, 119, 160, 226, 300, 404, 549, 727, 961, 1283, 1680, 2201, 2887, 3750, 4857, 6301, 8105, 10410, 13357, 17050, 21714, 27625, 34992, 44240, 55840, 70261, 88220, 110600, 138274, 172558, 214984, 267234
Offset: 1

Views

Author

Alford Arnold, May 25 2009, Jun 20 2009

Keywords

Comments

a(n) counts the following subset of the partitions (cf. A000041): the number being partitioned is odd, the minimum part is two
and the three largest parts match.
First differences of A161921.

Examples

			A161921 begins: 0, 0, 1, 2, 3, 7, 11, 17, 28, 43, 63, 96, 139, 199, 287, 406, 566, ...
Therefore a(n) begins 0, 0, 0, 1, 1, 1, 4, 4, 6, ..., counting 333; 3332; 33322; 555, 4443, 333222, 33333; etc.
		

Crossrefs

Programs

  • Mathematica
    Join[{0},Differences[Take[Differences[Table[PartitionsP[n],{n,0,100}],2],{2,-1,2}]]] (* Harvey P. Dale, Sep 02 2013 *)

Extensions

Extended and edited by Nathaniel Johnston, Apr 30 2011
Showing 1-3 of 3 results.