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 1-10 of 12 results. Next

A290247 Number of compositions (ordered partitions) of n^3 into cubes.

Original entry on oeis.org

1, 1, 2, 120, 290250, 107320441096, 21715974961480054078, 8487986089807555456140271121440, 22615863021403796876556069287242400147213424924, 1449638083412288206280215383952017948209203861522683138464747658192
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 24 2017

Keywords

Examples

			a(2) = 2 because 2^3 = 8 and we have [8], [1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; local i; if n=0 then 1
          else 0; for i while i^3<=n do %+b(n-i^3) od fi
        end:
    a:= n-> b(n^3):
    seq(a(n), n=0..10);  # Alois P. Heinz, Aug 12 2017
  • Mathematica
    Table[SeriesCoefficient[1/(1 - Sum[x^k^3, {k, 1, n}]), {x, 0, n^3}], {n, 0, 9}]

Formula

a(n) = [x^(n^3)] 1/(1 - Sum_{k>=1} x^(k^3)).
a(n) = A023358(A000578(n)).

A224677 Number of compositions of n*(n+1)/2 into sums of positive triangular numbers.

Original entry on oeis.org

1, 1, 2, 7, 40, 351, 4876, 104748, 3487153, 179921982, 14387581923, 1783124902639, 342504341570010, 101962565961894431, 47044167891731682278, 33640402686770010577421, 37282664267078280296013183, 64038780633654058635677191329, 170478465430659361252118580217675
Offset: 0

Views

Author

Paul D. Hanna, Apr 14 2013

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; local i; if n=0 then 1 else 0;
          for i while i*(i+1)/2<=n do %+b(n-i*(i+1)/2) od; %  fi
        end:
    a:= n-> b(n*(n+1)/2):
    seq(a(n), n=0..20);  # Alois P. Heinz, Feb 05 2018
  • Mathematica
    b[n_] := b[n] = If[n==0, 1, Sum[If[IntegerQ[Sqrt[8j+1]], b[n-j], 0], {j, 1, n}]];
    a[n_] := b[n(n+1)/2];
    a /@ Range[0, 20] (* Jean-François Alcover, Oct 31 2020, after Alois P. Heinz in A023361 *)
  • PARI
    {a(n)=polcoeff(1/(1-sum(r=1,n+1, x^(r*(r+1)/2)+x*O(x^(n*(n+1)/2)))), n*(n+1)/2)}
    for(n=0, 20, print1(a(n), ", "))

Formula

a(n) = A023361(n*(n+1)/2), where A023361(n) is the number of compositions of n into positive triangular numbers.
a(n) = [x^(n*(n+1)/2)] 1/(1 - Sum_{k>=1} x^(k*(k+1)/2)).

A337764 Number of compositions (ordered partitions) of the n-th n-gonal number into n-gonal numbers.

Original entry on oeis.org

1, 1, 2, 7, 124, 14371, 12842911, 103590035354, 8621925847489749, 8307493939404888703058, 102488432265617100812550713499, 17706351554929677399562928448484650120, 46435685450659378932235460132506329282776942795
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 19 2020

Keywords

Examples

			a(3) = 7 because the third triangular number is 6 and we have [6], [3, 3], [3, 1, 1, 1], [1, 3, 1, 1], [1, 1, 3, 1], [1, 1, 1, 3] and [1, 1, 1, 1, 1, 1].
		

Crossrefs

Formula

a(n) = [x^p(n,n)] 1 / (1 - Sum_{k=1..n} x^p(n,k)), where p(n,k) = k * (k * (n - 2) - n + 4) / 2 is the k-th n-gonal number.

A224679 Number of compositions of n^2 into sums of positive triangular numbers.

Original entry on oeis.org

1, 1, 3, 25, 546, 28136, 3487153, 1038115443, 742336894991, 1275079195875471, 5260826667789867957, 52137661179700350278531, 1241165848412448464485760897, 70972288312605764017275784402928, 9748291749334923037419108242002717050
Offset: 0

Views

Author

Paul D. Hanna, Apr 14 2013

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; local i; if n=0 then 1 else 0;
          for i while i*(i+1)/2<=n do %+b(n-i*(i+1)/2) od; %  fi
        end:
    a:= n-> b(n^2):
    seq(a(n), n=0..20);  # Alois P. Heinz, Feb 05 2018
  • Mathematica
    b[n_] := b[n] = Module[{i, j = If[n == 0, 1, 0]}, For[i = 1, i(i+1)/2 <= n, i++, j += b[n-i(i+1)/2]]; j];
    a[n_] := b[n^2];
    a /@ Range[0, 20] (* Jean-François Alcover, Nov 04 2020, after Alois P. Heinz *)
  • PARI
    {a(n)=polcoeff(1/(1-sum(r=1,n+1, x^(r*(r+1)/2)+x*O(x^(n^2)))), n^2)}
    for(n=0, 20, print1(a(n), ", "))

Formula

a(n) = A023361(n^2), where A023361(n) = number of compositions of n into positive triangular numbers.
a(n) = [x^(n^2)] 1/(1 - Sum_{k>=1} x^(k*(k+1)/2)).

A298640 Number of compositions (ordered partitions) of n^2 into squares > 1.

Original entry on oeis.org

1, 0, 1, 1, 2, 8, 12, 129, 874, 9630, 167001, 3043147, 72844510, 2423789655, 106665874384, 6156805673648, 470151743582651, 47558937432498729, 6363358599941131580, 1126147544855148769425, 263646401550138303553708, 81649922556593759124887197
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 24 2018

Keywords

Examples

			a(5) = 8 because we have [25], [16, 9], [9, 16], [9, 4, 4, 4, 4], [4, 9, 4, 4, 4], [4, 4, 9, 4, 4], [4, 4, 4, 9, 4] and [4, 4, 4, 4, 9].
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1,
          add(b(n-j^2), j=2..isqrt(n)))
        end:
    a:= n-> b(n^2):
    seq(a(n), n=0..25);  # Alois P. Heinz, Feb 05 2018
  • Mathematica
    b[n_] := b[n] = If[n == 0, 1, Sum[b[n - j^2], {j, 2, Floor @ Sqrt[n]}]];
    a[n_] := b[n^2];
    Table[a[n], {n, 0, 25}] (* Jean-François Alcover, May 21 2018, after Alois P. Heinz *)

Formula

a(n) = [x^(n^2)] 1/(1 - Sum_{k>=2} x^(k^2)).
a(n) = A280542(A000290(n)).

A224607 a(n) = A219331(n^2).

Original entry on oeis.org

1, 5, 28, 269, 6181, 286790, 26808447, 5037694829, 1902773895751, 1444565587750055, 2204357811343981558, 6761166975496300074014, 41682712965722542326438411, 516517498759950258411494666787, 12864972023450485679400300069493738
Offset: 1

Views

Author

Paul D. Hanna, Apr 12 2013

Keywords

Comments

A219331 is the logarithmic derivative of A006456, where A006456(n) is the number of compositions of n into sums of squares.

Examples

			L.g.f.: L(x) = x + 5*x^2/2 + 28*x^3/3 + 269*x^4/4 + 6181*x^5/5 + 286790*x^6/6 +...
where
exp(L(x)) = 1 + x + 3*x^2 + 12*x^3 + 81*x^4 + 1335*x^5 + 49309*x^6 + 3882180*x^7 +...+ A224608(n)*x^n +...
		

Crossrefs

Programs

  • PARI
    {a(n)=n^2*polcoeff(-log(1-sum(r=1,n,x^(r^2)+x*O(x^(n^2)))),n^2)}
    for(n=1,30,print1(a(n),", "))

Formula

Logarithmic derivative of A224608.

A224608 G.f.: exp( Sum_{n>=1} A219331(n^2)*x^n/n ).

Original entry on oeis.org

1, 1, 3, 12, 81, 1335, 49309, 3882180, 633703214, 212061201327, 144669917959584, 200541263416077021, 563631413420071614333, 3206926569346230863485855, 36897315109526505791310840932, 857701705296285206387609947414980, 40254707002970300021370965171570478599
Offset: 0

Views

Author

Paul D. Hanna, Apr 12 2013

Keywords

Comments

A219331 is the logarithmic derivative of A006456, where A006456(n) is the number of compositions of n into sums of squares.

Examples

			G.f.: A(x) = 1 + x + 3*x^2 + 12*x^3 + 81*x^4 + 1335*x^5 + 49309*x^6 +...
where
log(A(x)) = x + 5*x^2/2 + 28*x^3/3 + 269*x^4/4 + 6181*x^5/5 + 286790*x^6/6 +...+ A219331(n^2)*x^n/n +...
		

Crossrefs

Programs

  • PARI
    {A219331(n)=n*polcoeff(-log(1-sum(r=1,sqrtint(n+1),x^(r^2)+x*O(x^n))),n)}
    {a(n)=polcoeff(exp(sum(m=1,n,A219331(m^2)*x^m/m)+x*O(x^n)),n)}
    for(n=0,20,print1(a(n),", "))

Formula

Logarithmic derivative yields A224607, where A224607(n) = A219331(n^2).

A331884 Number of compositions (ordered partitions) of n^2 into distinct squares.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 7, 1, 31, 123, 151, 121, 897, 7351, 5415, 14881, 48705, 150583, 468973, 1013163, 1432471, 1730023, 50432107, 14925241, 125269841, 74592537, 241763479, 213156871, 895153173, 7716880623, 2681163865, 3190865761, 22501985413, 116279718801
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 30 2020

Keywords

Examples

			a(5) = 3 because we have [25], [16, 9] and [9, 16].
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, p) option remember;
          `if`(i*(i+1)*(2*i+1)/6n, 0, b(n-i^2, i-1, p+1))+b(n, i-1, p)))
        end:
    a:= n-> b(n^2, n, 0):
    seq(a(n), n=0..35);  # Alois P. Heinz, Jan 30 2020
  • Mathematica
    b[n_, i_, p_] := b[n, i, p] = If[i(i+1)(2i+1)/6 < n, 0, If[n == 0, p!, If[i^2 > n, 0, b[n - i^2, i - 1, p + 1]] + b[n, i - 1, p]]];
    a[n_] := b[n^2, n, 0];
    a /@ Range[0, 35] (* Jean-François Alcover, Nov 08 2020, after Alois P. Heinz *)

Formula

a(n) = A331844(A000290(n)).

Extensions

a(24)-a(34) from Alois P. Heinz, Jan 30 2020

A347590 Number of compositions (ordered partitions) of n^2 into at most n squares.

Original entry on oeis.org

1, 1, 1, 4, 2, 20, 188, 1031, 8777, 62528, 437160, 4185739, 38642386, 383969125, 4149154916, 45160025119, 514181220266, 6133093344169, 75135177511922, 962729735639323, 12745694628358530, 173304634479902187, 2433186864257121180, 35030916937968941062
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 08 2021

Keywords

Crossrefs

A232266 Triangle where T(n,k) = number of compositions of n^2 - k^2 into sums of squares for k=0..n, n>=0, as read by rows.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 11, 7, 3, 1, 124, 88, 30, 5, 1, 2870, 2024, 710, 124, 11, 1, 133462, 94137, 33033, 5767, 502, 22, 1, 12477207, 8800750, 3088365, 539192, 46832, 2024, 43, 1, 2344649612, 1653790807, 580347968, 101321507, 8800750, 380315, 8176, 88, 1, 885591183971, 624648802700, 219201637352, 38269865019, 3324109524, 143647802, 3088365, 33033, 175, 1
Offset: 0

Views

Author

Paul D. Hanna, Nov 21 2013

Keywords

Examples

			Triangle begins:
1;
1, 1;
2, 1, 1;
11, 7, 3, 1;
124, 88, 30, 5, 1;
2870, 2024, 710, 124, 11, 1;
133462, 94137, 33033, 5767, 502, 22, 1;
12477207, 8800750, 3088365, 539192, 46832, 2024, 43, 1;
2344649612, 1653790807, 580347968, 101321507, 8800750, 380315, 8176, 88, 1;
885591183971, 624648802700, 219201637352, 38269865019, 3324109524, 143647802, 3088365, 33033, 175, 1; ...
where T(n,k) = coefficient of x^(n^2-k^2) in the series:
1/(1 - x - x^4 - x^9 - x^16 - x^25 - x^36 -...- x^(n^2) -...) = 1 + x + x^2 + x^3 + 2*x^4 + 3*x^5 + 4*x^6 + 5*x^7 + 7*x^8 + 11*x^9 + 16*x^10 + 22*x^11 + 30*x^12 + 43*x^13 + 62*x^14 + 88*x^15 + 124*x^16 + 175*x^17 + 249*x^18 + 354*x^19 + 502*x^20 + 710*x^21 + 1006*x^22 + 1427*x^23 + 2024*x^24 + 2870*x^25 +...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=polcoeff(1/(1-sum(m=1,n+1,x^(m^2))+x*O(x^(n^2-k^2))),n^2-k^2)}
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))

Formula

T(n,k) = A006456(n^2-k^2).
T(n,k) = [x^(n^2-k^2)] 1/(1 - Sum_{j>=1} x^(j^2)).
T(n,0) = Sum_{k=1..n} T(n,k) for n>=1.
Showing 1-10 of 12 results. Next