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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A331846 Number of compositions (ordered partitions) of n into distinct squarefree parts.

Original entry on oeis.org

1, 1, 1, 3, 2, 3, 9, 5, 12, 16, 21, 41, 42, 49, 59, 79, 130, 231, 230, 295, 226, 495, 609, 699, 1472, 1042, 1377, 2308, 2982, 3425, 3879, 4877, 7156, 7189, 13531, 14797, 13570, 19551, 27667, 30327, 36382, 47519, 60783, 70561, 78330, 136988, 121659, 174851
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 29 2020

Keywords

Examples

			a(7) = 5 because we have [7], [6, 1], [5, 2], [2, 5] and [1, 6].
		

Crossrefs

A331847 Number of compositions (ordered partitions) of n into distinct prime powers (1 excluded).

Original entry on oeis.org

1, 0, 1, 1, 1, 3, 2, 5, 3, 11, 10, 13, 18, 19, 52, 30, 61, 77, 114, 109, 146, 260, 318, 341, 356, 631, 666, 927, 848, 1849, 1978, 2305, 2213, 3560, 4302, 4748, 5588, 6779, 13952, 9044, 15534, 16897, 25084, 20731, 29524, 34882, 49360, 50765, 55112, 106903, 83652, 128552, 106638
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 29 2020

Keywords

Examples

			a(10) = 10 because we have [8, 2], [7, 3], [5, 3, 2], [5, 2, 3], [3, 7], [3, 5, 2], [3, 2, 5], [2, 8], [2, 5, 3] and [2, 3, 5].
		

Crossrefs

A332032 G.f.: Sum_{k>=1} k! * x^(k^2) / (1 - x^(2*k)).

Original entry on oeis.org

1, 0, 1, 2, 1, 0, 1, 2, 7, 0, 1, 2, 1, 0, 7, 26, 1, 0, 1, 2, 7, 0, 1, 26, 121, 0, 7, 2, 1, 0, 1, 26, 7, 0, 121, 722, 1, 0, 7, 26, 1, 0, 1, 2, 127, 0, 1, 746, 5041, 0, 7, 2, 1, 0, 121, 26, 7, 0, 1, 722, 1, 0, 5047, 40346, 121, 0, 1, 2, 7, 0, 1, 746, 1, 0, 127
Offset: 1

Views

Author

Ilya Gutkovskiy, Feb 05 2020

Keywords

Comments

Number of compositions (ordered partitions) of n into distinct odd parts, where every odd part between the largest and smallest appears.

Examples

			a(9) = 7 because we have [9], [5, 3, 1], [5, 1, 3], [3, 5, 1], [3, 1, 5], [1, 5, 3] and [1, 3, 5].
a(12) = 2 because we have [7, 5], and [5, 7]. - _Antti Karttunen_, Dec 15 2021
		

Crossrefs

Cf. A016825 (positions of 0's), A032021, A034178, A038548, A107461, A220400.
Coincides with A332031 on odd numbers.

Programs

  • Mathematica
    nmax = 75; CoefficientList[Series[Sum[k! x^(k^2)/(1 - x^(2 k)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
  • PARI
    A332032(n) = sumdiv(n, d, if(!((n+d)%2) && !((n+(n/d))%2) && (d<=(n/d)), d!, 0)); \\ Antti Karttunen, Dec 15 2021

Formula

From Antti Karttunen, Dec 15 2021: (Start)
a(n) = Sum_{d|n, d <= n/d, and both d and n/d are of the same parity as n} d!.
a(2n-1) = A332031(2n-1) for all n >= 1.
(End)

A218694 Carlitz compositions of n into odd parts.

Original entry on oeis.org

1, 1, 0, 1, 2, 2, 2, 3, 6, 9, 10, 13, 22, 32, 40, 56, 86, 122, 164, 229, 332, 474, 656, 914, 1310, 1867, 2604, 3648, 5184, 7346, 10318, 14506, 20516, 29022, 40880, 57548, 81260, 114810, 161864, 228092, 321892, 454444, 640954, 903715, 1274998, 1799320, 2538218, 3579714, 5049954, 7125359, 10051844
Offset: 0

Views

Author

Joerg Arndt, Nov 04 2012

Keywords

Comments

Carlitz compositions are compositions where adjacent parts are distinct (see A003242).

Examples

			There are a(12) = 22 such compositions of 12:
[ 1]  1 3 1 3 1 3
[ 2]  1 3 1 7
[ 3]  1 3 5 3
[ 4]  1 3 7 1
[ 5]  1 5 1 5
[ 6]  1 7 1 3
[ 7]  1 7 3 1
[ 8]  1 11
[ 9]  3 1 3 1 3 1
[10]  3 1 3 5
[11]  3 1 5 3
[12]  3 1 7 1
[13]  3 5 1 3
[14]  3 5 3 1
[15]  3 9
[16]  5 1 5 1
[17]  5 3 1 3
[18]  5 7
[19]  7 1 3 1
[20]  7 5
[21]  9 3
[22]  11 1
		

Crossrefs

Cf. A003242 (Carlitz compositions), A032021 (compositions into distinct odd parts), A032020 (compositions into distinct parts).

Programs

  • Maple
    b:= proc(n, t) option remember; `if`(n=0, 1,
           add(`if`(j=t or irem(j, 2)=0, 0, b(n-j, j)), j=1..n))
        end:
    a:= n-> b(n, 0):
    seq(a(n), n=0..70);  # Alois P. Heinz, Nov 08 2012
  • Mathematica
    nn=20;CoefficientList[Series[1/(1-Sum[z^(2j+1)/(1+z^(2j+1)),{j,0,nn}]),{z,0,nn}],z] (* Geoffrey Critzer, Nov 21 2013 *)

Formula

G.f.: 1/( 1 - Sum_{j>=0} x^(2j+1)/(1 + x^(2j+1)) ). - Geoffrey Critzer, Nov 21 2013
a(n) ~ c / r^n, where r = 0.708865489663179258570259601255070249415... is the root of the equation sum_{j>=0} x^(2j+1)/(1 + x^(2j+1)) = 1, c = 0.3391570949344217123793275284038135702369824934927187... . - Vaclav Kotesovec, Aug 22 2014

A332309 Number of compositions (ordered partitions) of n into distinct parts where no part is a multiple of 3.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 4, 9, 9, 6, 15, 17, 38, 29, 53, 70, 65, 91, 150, 229, 277, 236, 439, 489, 514, 897, 993, 1632, 1521, 2339, 2972, 3257, 4121, 5992, 5303, 7729, 10932, 15157, 17653, 18398, 26305, 31683, 34408, 51885, 58173, 61098, 90519, 101249, 143402, 156905
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 09 2020

Keywords

Examples

			a(9) = 6 because we have [8, 1], [7, 2], [5, 4], [4, 5], [2, 7] and [1, 8].
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(i*(i+1)/2 b(n$2, 0):
    seq(a(n), n=0..55);  # Alois P. Heinz, Feb 09 2020
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i(i+1)/2 < n, 0, If[n == 0, p!, Sum[b[n - i j, i - 1, p + j], {j, 0, Min[Mod[i, 3], 1, n/i]}]]];
    a[n_] := b[n, n, 0];
    a /@ Range[0, 55] (* Jean-François Alcover, Nov 09 2020, after Alois P. Heinz *)

A332311 Number of compositions (ordered partitions) of n into distinct parts where no part is a multiple of 5.

Original entry on oeis.org

1, 1, 1, 3, 3, 4, 9, 11, 11, 19, 44, 31, 61, 87, 117, 144, 279, 311, 389, 541, 640, 1003, 1225, 2145, 2493, 3452, 3507, 5417, 6671, 8821, 11580, 17959, 21043, 26289, 34797, 41536, 59637, 72707, 85871, 110947, 172472, 175873, 249691, 327801, 418779, 512748
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 09 2020

Keywords

Examples

			a(6) = 9 because we have [6], [4, 2], [3, 2, 1], [3, 1, 2], [2, 4], [2, 3, 1], [2, 1, 3], [1, 3, 2] and [1, 2, 3].
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, p) option remember; `if`(i*(i+1)/2 b(n$2, 0):
    seq(a(n), n=0..55);  # Alois P. Heinz, Feb 09 2020
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i(i+1)/2 < n, 0, If[n == 0, p!, Sum[b[n - i j, i - 1, p + j], {j, 0, Min[Mod[i, 5], 1, n/i]}]]];
    a[n_] := b[n, n, 0];
    a /@ Range[0, 55] (* Jean-François Alcover, Nov 17 2020, after Alois P. Heinz *)

A339086 Number of compositions (ordered partitions) of n into distinct parts congruent to 1 mod 5.

Original entry on oeis.org

1, 1, 0, 0, 0, 0, 1, 2, 0, 0, 0, 1, 2, 0, 0, 0, 1, 4, 6, 0, 0, 1, 4, 6, 0, 0, 1, 6, 12, 0, 0, 1, 6, 18, 24, 0, 1, 8, 24, 24, 0, 1, 8, 30, 48, 0, 1, 10, 42, 72, 0, 1, 10, 48, 120, 120, 1, 12, 60, 144, 120, 1, 12, 72, 216, 240, 1, 14, 84, 264, 360, 1, 14, 96, 360, 600, 1, 16, 114
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 23 2020

Keywords

Examples

			a(18) = 6 because we have [11, 6, 1], [11, 1, 6], [6, 11, 1], [6, 1, 11], [1, 11, 6] and [1, 6, 11].
		

Crossrefs

Programs

  • Mathematica
    nmax = 78; CoefficientList[Series[Sum[k! x^(k (5 k - 3)/2)/Product[1 - x^(5 j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=0} k! * x^(k*(5*k - 3)/2) / Product_{j=1..k} (1 - x^(5*j)).

A339087 Number of compositions (ordered partitions) of n into distinct parts congruent to 4 mod 5.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 2, 1, 0, 0, 0, 2, 1, 0, 0, 0, 4, 1, 0, 0, 6, 4, 1, 0, 0, 6, 6, 1, 0, 0, 12, 6, 1, 0, 0, 18, 8, 1, 0, 24, 24, 8, 1, 0, 24, 30, 10, 1, 0, 48, 42, 10, 1, 0, 72, 48, 12, 1, 0, 120, 60, 12, 1, 120, 144, 72, 14, 1, 120, 216, 84, 14, 1, 240
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 23 2020

Keywords

Examples

			a(27) = 6 because we have [14, 9, 4], [14, 4, 9], [9, 14, 4], [9, 4, 14], [4, 14, 9] and [4, 9, 14].
		

Crossrefs

Programs

  • Mathematica
    nmax = 80; CoefficientList[Series[Sum[k! x^(k (5 k + 3)/2)/Product[1 - x^(5 j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=0} k! * x^(k*(5*k + 3)/2) / Product_{j=1..k} (1 - x^(5*j)).

A339088 Number of compositions (ordered partitions) of n into distinct parts congruent to 1 mod 6.

Original entry on oeis.org

1, 1, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 1, 4, 6, 0, 0, 0, 1, 4, 6, 0, 0, 0, 1, 6, 12, 0, 0, 0, 1, 6, 18, 24, 0, 0, 1, 8, 24, 24, 0, 0, 1, 8, 30, 48, 0, 0, 1, 10, 42, 72, 0, 0, 1, 10, 48, 120, 120, 0, 1, 12, 60, 144, 120, 0, 1, 12, 72, 216, 240, 0, 1, 14, 84, 264, 360
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 23 2020

Keywords

Examples

			a(21) = 6 because we have [13, 7, 1], [13, 1, 7], [7, 13, 1], [7, 1, 13], [1, 13, 7] and [1, 7, 13].
		

Crossrefs

Programs

  • Mathematica
    nmax = 83; CoefficientList[Series[Sum[k! x^(k (3 k - 2))/Product[1 - x^(6 j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=0} k! * x^(k*(3*k - 2)) / Product_{j=1..k} (1 - x^(6*j)).

A339089 Number of compositions (ordered partitions) of n into distinct parts congruent to 5 mod 6.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 0, 4, 1, 0, 0, 0, 6, 4, 1, 0, 0, 0, 6, 6, 1, 0, 0, 0, 12, 6, 1, 0, 0, 0, 18, 8, 1, 0, 0, 24, 24, 8, 1, 0, 0, 24, 30, 10, 1, 0, 0, 48, 42, 10, 1, 0, 0, 72, 48, 12, 1, 0, 0, 120, 60, 12, 1, 0, 120, 144
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 23 2020

Keywords

Examples

			a(33) = 6 because we have [17, 11, 5], [17, 5, 11], [11, 17, 5], [11, 5, 17], [5, 17, 11] and [5, 11, 17].
		

Crossrefs

Programs

  • Mathematica
    nmax = 86; CoefficientList[Series[Sum[k! x^(k (3 k + 2))/Product[1 - x^(6 j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=0} k! * x^(k*(3*k + 2)) / Product_{j=1..k} (1 - x^(6*j)).
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