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.

Previous Showing 21-29 of 29 results.

A237272 Number of overcompositions of n that contain at least two parts in increasing order and that contain at least one overlined part.

Original entry on oeis.org

0, 0, 0, 3, 9, 27, 83, 211, 522, 1222, 2874, 6496, 14593, 32185, 70423, 153024, 330195, 708933, 1514821, 3224134, 6836547, 14455648, 30475210, 64096487, 134493519, 281642590, 588642240, 1228160742, 2558300338, 5321065857, 11051923912, 22925167566
Offset: 0

Views

Author

Omar E. Pol, Feb 09 2014

Keywords

Comments

Number of overcompositions of n minus the number of overpartitions of n plus the number of partitions of n minus the number of compositions of n.

Crossrefs

Formula

a(n) = A236002(n) - A015128(n) + A000041(n) - A011782(n) = A236002(n) - A230441(n) - A011782(n) = A237045(n) - A056823(n).

A332871 Number of compositions of n whose run-lengths are not weakly increasing.

Original entry on oeis.org

0, 0, 0, 0, 1, 4, 8, 24, 55, 128, 282, 625, 1336, 2855, 6000, 12551, 26022, 53744, 110361, 225914, 460756, 937413, 1902370, 3853445, 7791647, 15732468, 31725191, 63907437, 128613224, 258626480, 519700800, 1043690354, 2094882574, 4202903667, 8428794336, 16897836060
Offset: 0

Views

Author

Gus Wiseman, Feb 29 2020

Keywords

Comments

A composition of n is a finite sequence of positive integers summing to n.
Also compositions whose run-lengths are not weakly decreasing.

Examples

			The a(4) = 1 through a(6) = 8 compositions:
  (112)  (113)   (114)
         (221)   (1113)
         (1112)  (1131)
         (1121)  (1221)
                 (2112)
                 (11112)
                 (11121)
                 (11211)
For example, the composition (2,1,1,2) has run-lengths (1,2,1), which are not weakly increasing, so (2,1,1,2) is counted under a(6).
		

Crossrefs

The version for the compositions themselves (not run-lengths) is A056823.
The version for unsorted prime signature is A112769, with dual A071365.
The case without weakly decreasing run-lengths either is A332833.
The complement is counted by A332836.
Compositions that are not unimodal are A115981.
Compositions with equal run-lengths are A329738.
Compositions whose run-lengths are not unimodal are A332727.

Programs

  • Mathematica
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],!LessEqual@@Length/@Split[#]&]],{n,0,10}]

Formula

a(n) = 2^(n - 1) - A332836(n).

Extensions

Terms a(21) and beyond from Andrew Howroyd, Dec 30 2020

A375297 Number of integer compositions of n matching both of the dashed patterns 23-1 and 1-32.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 21, 68, 199, 545, 1410, 3530, 8557, 20255, 46968, 107135, 240927, 535379, 1177435, 2566618, 5551456
Offset: 0

Views

Author

Gus Wiseman, Aug 23 2024

Keywords

Comments

Also the number of integer compositions of n whose leaders of maximal weakly increasing runs are not weakly decreasing and whose reverse satisfies the same condition.

Examples

			The a(0) = 0 through a(11) = 21 compositions:
  .  .  .  .  .  .  .  .  .  (12321)  (1342)    (1352)
                                      (2431)    (2531)
                                      (12421)   (11342)
                                      (13231)   (12431)
                                      (112321)  (12521)
                                      (123211)  (13241)
                                                (13421)
                                                (14231)
                                                (23132)
                                                (24311)
                                                (112421)
                                                (113231)
                                                (122321)
                                                (123212)
                                                (123221)
                                                (124211)
                                                (132311)
                                                (212321)
                                                (1112321)
                                                (1123211)
                                                (1232111)
		

Crossrefs

For leaders of identical runs we have A332834.
For just one of the two conditions we have A374636, ranks A375137/A375138.
These compositions are ranked by A375407.
A003242 counts anti-runs, ranks A333489.
A011782 counts compositions.
A106356 counts compositions by number of maximal anti-runs.
A238130, A238279, A333755 count compositions by number of runs.
A274174 counts contiguous compositions, ranks A374249.
A335456 counts patterns matched by compositions.

Programs

  • Mathematica
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], MatchQ[#,{_,y_,z_,_,x_,_}/;x_,x_,_,z_,y_,_}/;x
    				

A375406 Number of integer compositions of n that match the dashed pattern 3-12.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 4, 14, 41, 110, 278, 673, 1576, 3599, 8055, 17732, 38509, 82683, 175830, 370856, 776723, 1616945, 3348500, 6902905, 14174198, 29004911, 59175625, 120414435, 244468774, 495340191, 1001911626, 2023473267, 4081241473, 8222198324, 16548146045, 33276169507
Offset: 0

Views

Author

Gus Wiseman, Aug 22 2024

Keywords

Comments

First differs from the non-dashed version A335514 at a(9) = 41, A335514(9) = 42, due to the composition (3,1,3,2).
Also the number of integer compositions of n whose leaders of weakly decreasing runs are not weakly increasing. For example, the composition q = (1,1,2,1,2,2,1,3) has maximal weakly decreasing runs ((1,1),(2,1),(2,2,1),(3)), with leaders (1,2,2,3), which are weakly increasing, so q is not counted under a(13); also q does not match 3-12. On the other hand, the reverse is (3,1,2,2,1,2,1,1), with maximal weakly decreasing runs ((3,1),(2,2,1),(2,1,1)), with leaders (3,2,2), which are not weakly increasing, so it is counted under a(13); meanwhile it matches 3-12, as required.

Examples

			The a(0) = 0 through a(8) = 14 compositions:
  .  .  .  .  .  .  (312)  (412)   (413)
                           (1312)  (512)
                           (3112)  (1412)
                           (3121)  (2312)
                                   (3122)
                                   (3212)
                                   (4112)
                                   (4121)
                                   (11312)
                                   (13112)
                                   (13121)
                                   (31112)
                                   (31121)
                                   (31211)
		

Crossrefs

For leaders of identical runs we have A056823.
The complement is counted by A188900.
The non-dashed version is A335514, ranks A335479.
Ranks are positions of non-weakly increasing rows in A374740.
A003242 counts anti-run compositions, ranks A333489.
A011782 counts compositions.
Counting compositions by number of runs: A238130, A238279, A333755.
A373949 counts compositions by run-compressed sum, opposite A373951.

Programs

  • Mathematica
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], !LessEqual@@First/@Split[#,GreaterEqual]&]],{n,0,15}]
    - or -
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], MatchQ[#,{_,z_,_,x_,y_,_}/;x
    				

Formula

a(n>0) = 2^(n-1) - A188900(n).

A376263 Number of strict integer compositions of n whose leaders of increasing runs are increasing.

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 5, 6, 8, 11, 18, 21, 30, 38, 52, 77, 96, 126, 167, 217, 278, 402, 488, 647, 822, 1073, 1340, 1747, 2324, 2890, 3695, 4690, 5924, 7469, 9407, 11718, 15405, 18794, 23777, 29507, 37188, 45720, 57404, 70358, 87596, 110672, 135329, 167018, 206761, 254200, 311920
Offset: 0

Views

Author

Gus Wiseman, Sep 18 2024

Keywords

Comments

The leaders of increasing runs of a sequence are obtained by splitting it into maximal increasing subsequences and taking the first term of each.

Examples

			The a(1) = 1 through a(9) = 11 compositions:
 (1) (2) (3)   (4)   (5)   (6)     (7)     (8)     (9)
         (1,2) (1,3) (1,4) (1,5)   (1,6)   (1,7)   (1,8)
                     (2,3) (2,4)   (2,5)   (2,6)   (2,7)
                           (1,2,3) (3,4)   (3,5)   (3,6)
                           (1,3,2) (1,2,4) (1,2,5) (4,5)
                                   (1,4,2) (1,3,4) (1,2,6)
                                           (1,4,3) (1,3,5)
                                           (1,5,2) (1,5,3)
                                                   (1,6,2)
                                                   (2,3,4)
                                                   (2,4,3)
		

Crossrefs

For less-greater or greater-less we have A294617.
This is a strict case of A374688, weak version A374635.
The strict less-greater version is A374689, weak version A189076.
A003242 counts anti-run compositions, ranks A333489.
A011782 counts compositions, strict A032020.
A238130, A238279, A333755 count compositions by number of runs.
A373949 counts compositions by run-compressed sum, opposite A373951.
A374700 counts compositions by sum of leaders of strictly increasing runs.

Programs

  • Mathematica
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], UnsameQ@@#&&Less@@First/@Split[#,Less]&]],{n,0,15}]
  • PARI
    \\ here Q(n) gives n-th row of A008289.
    Q(n)={Vecrev(polcoef(prod(k=1, n, 1 + y*x^k, 1 + O(x*x^n)), n)/y)}
    a(n)={if(n==0, 1, my(r=Q(n), s=Vec(serlaplace(exp(exp(x+O(x^#r))- 1)))); sum(k=1, #r, r[k]*s[k]))} \\ Andrew Howroyd, Sep 18 2024

Formula

a(n) = Sum_{k>=1} A008289(n,k)*A000110(k-1) for n > 0. - Andrew Howroyd, Sep 18 2024

Extensions

a(26) onwards from Andrew Howroyd, Sep 18 2024

A174523 Triangle T(n,1) = A117989(n+1) in the first column and recursively T(n,k) = 2*T(n-1,k-1).

Original entry on oeis.org

1, 1, 2, 3, 2, 4, 3, 6, 4, 8, 7, 6, 12, 8, 16, 8, 14, 12, 24, 16, 32, 14, 16, 28, 24, 48, 32, 64, 18, 28, 32, 56, 48, 96, 64, 128, 28, 36, 56, 64, 112, 96, 192, 128, 256, 35, 56, 72, 112, 128, 224, 192, 384, 256, 512, 53, 70, 112, 144, 224, 256
Offset: 1

Views

Author

Alford Arnold, Mar 30 2010

Keywords

Examples

			1;
1,2;
3,2,4;
3,6,4,8;
7,6,12,8,16;
8,14,12,24,16,32;
14,16,28,24,48,32,64;
18,28,32,56,48,96,64,128;
28,36,56,64,112,96,192,128,256;
35,56,72,112,128,224,192,384,256,512;
		

Crossrefs

Cf. A056823 (row sums).

Programs

  • Maple
    A174523 := proc(n,k)
        option remember;
        if k = 1 then
            A117989(n+1) ;
        elif k > n then
            0;
        else
            2*procname(n-1,k-1) ;
        end if;
    end proc: # R. J. Mathar, May 19 2016

Extensions

Edited by R. J. Mathar, May 17 2016

A229935 Total number of parts in all compositions of n with at least two parts in increasing order.

Original entry on oeis.org

0, 0, 0, 2, 8, 28, 77, 202, 490, 1152, 2624, 5869, 12913, 28116, 60660, 130004, 277065, 587859, 1242540, 2617942, 5500394, 11528284, 24109349, 50321442, 104844426, 218086957, 452963310, 939496802, 1946122511, 4026488387, 8321444573, 17179801049, 35433395265
Offset: 0

Views

Author

Omar E. Pol, Oct 14 2013

Keywords

Comments

Total number of parts in all compositions of n that are not partitions of n (see example).

Examples

			For n = 4 the table shows both the compositions and the partitions of 4. There are three compositions of 4 that are not partitions of 4.
----------------------------------------------------
Compositions       Partitions       Number of parts
----------------------------------------------------
[1, 1, 1, 1]   =   [1, 1, 1, 1]
[2, 1, 1]      =   [2, 1, 1]
[1, 2, 1]                                 3
[3, 1]         =   [3, 1]
[1, 1, 2]                                 3
[2, 2]         =   [2, 2]
[1, 3]                                    2
[4]            =   [4]
----------------------------------------------------
Total                                     8
.
A partition of a positive integer n is any nonincreasing sequence of positive integers which sum to n, ence the compositions of 4 that are not partitions of 4 are [1, 2, 1], [1, 1, 2] and [1, 3]. The total number of parts of these compositions is 3 + 3 + 2 = 8. On the other hand the total number of parts in all compositions of 4 is A001792(4-1) = 20, and the total number of parts in all partitions of 4 is A006128(4) = 12, so a(4) = 20 - 12 = 8.
		

Crossrefs

Formula

a(n) = A001792(n-1) - A006128(n), n >= 1.

A229936 Sum of all parts of all compositions of n with at least two parts in increasing order.

Original entry on oeis.org

0, 0, 0, 3, 12, 45, 126, 343, 848, 2034, 4700, 10648, 23652, 51935, 112798, 243120, 520592, 1109063, 2352366, 4971426, 10473220, 22003464, 46115300, 96440127, 201288792, 419381450, 872351896, 1811858058, 3757992280, 7784495839, 16105959240, 33285784442
Offset: 0

Views

Author

Omar E. Pol, Oct 14 2013

Keywords

Comments

Sum of all parts of all compositions of n that are not partitions of n (see example).

Examples

			For n = 4 the table shows both the compositions and the partitions of 4. There are three compositions of 4 that are not partitions of 4.
----------------------------------------------------
Compositions       Partitions      Sum of all parts
----------------------------------------------------
[1, 1, 1, 1]   =   [1, 1, 1, 1]
[2, 1, 1]      =   [2, 1, 1]
[1, 2, 1]                                 4
[3, 1]         =   [3, 1]
[1, 1, 2]                                 4
[2, 2]         =   [2, 2]
[1, 3]                                    4
[4]            =   [4]
----------------------------------------------------
Total                                    12
.
A partition of a positive integer n is any nonincreasing sequence of positive integers which sum to n, ence the compositions of 4 that are not partitions of 4 are [1, 2, 1], [1, 1, 2] and [1, 3]. The sum of all parts of these compositions is 1+3+1+2+1+1+1+2 = 3*4 = 12. On the other hand the sum of all parts in all compositions of 4 is A001787(4) = 32, and the sum of all parts in all partitions of 4 is A066186(4) = 20, so a(4) = 32 - 20 = 12.
		

Crossrefs

Formula

a(n) = n*A056823(n) = n*(A011782(n) - A000041(n)).
a(n) = A001787(n) - A066186(n), n >= 1.

A337698 Number of compositions of n that are not strictly increasing.

Original entry on oeis.org

0, 0, 1, 2, 6, 13, 28, 59, 122, 248, 502, 1012, 2033, 4078, 8170, 16357, 32736, 65498, 131026, 262090, 524224, 1048500, 2097063, 4194200, 8388486, 16777074, 33554267, 67108672, 134217506, 268435200, 536870616, 1073741484, 2147483258, 4294966848, 8589934080
Offset: 0

Views

Author

Gus Wiseman, Oct 06 2020

Keywords

Examples

			The a(2) = 1 through a(5) = 13 compositions:
  (11)  (21)   (22)    (32)
        (111)  (31)    (41)
               (112)   (113)
               (121)   (122)
               (211)   (131)
               (1111)  (212)
                       (221)
                       (311)
                       (1112)
                       (1121)
                       (1211)
                       (2111)
                       (11111)
		

Crossrefs

A000009 counts the complement.
A047967 is the unordered version.
A056823 is the weak version.
A140106 counts the unordered case of length 3.
A242771 counts the case of length 3.
A333255 is the complement of a ranking sequence (using standard compositions A066099) for these compositions.
A337481 counts these compositions that are not strictly decreasing.
A337482 counts these compositions that are not weakly decreasing.
A001523 counts unimodal compositions, with complement A115981.
A007318 and A097805 count compositions by length.
A218004 counts strictly increasing or weakly decreasing compositions.

Programs

  • Mathematica
    Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],!Less@@#&]],{n,0,15}]

Formula

a(n) = 2^(n-1) - A000009(n) for n > 0.
Previous Showing 21-29 of 29 results.