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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A317880 Number of series-reduced free pure symmetric identity multifunctions (with empty expressions allowed) with one atom and n positions.

Original entry on oeis.org

1, 1, 1, 1, 2, 4, 8, 16, 33, 70, 152, 333, 735, 1635, 3668, 8285, 18823, 42970, 98535, 226870, 524290, 1215641, 2827203, 6593432, 15416197, 36129894, 84860282, 199719932, 470930802, 1112388190, 2631903295, 6236669381, 14800078408, 35169529363, 83680908692
Offset: 1

Views

Author

Gus Wiseman, Aug 09 2018

Keywords

Comments

A series-reduced free pure symmetric identity multifunction (with empty expressions allowed) (SROI) is either (case 1) the leaf symbol "o", or (case 2) a possibly empty expression of the form h[g_1, ..., g_k] where h is an SROI, k is an integer greater than or equal to 0 but not equal to 1, each of the g_i for i = 1, ..., k is an SROI, and for i < j we have g_i < g_j under a canonical total ordering such as the Mathematica ordering of expressions. The number of positions in an SROI is the number of brackets [...] plus the number of o's.
Also the number of series-reduced orderless identity Mathematica expressions with one atom and n positions.

Examples

			The a(7) = 8 SROIs:
  o[o,o[][][]]
  o[o[],o[][]]
  o[][o,o[][]]
  o[][][o,o[]]
  o[o,o[][]][]
  o[][o,o[]][]
  o[o,o[]][][]
  o[][][][][][]
		

Crossrefs

Programs

  • Mathematica
    allIdExprSR[n_]:=If[n==1,{"o"},Join@@Cases[Table[PR[k,n-k-1],{k,n-1}],PR[h_,g_]:>Join@@Table[Apply@@@Tuples[{allIdExprSR[h],Select[Union[Sort/@Tuples[allIdExprSR/@p]],UnsameQ@@#&]}],{p,If[g==0,{{}},Rest[IntegerPartitions[g]]]}]]];
    Table[Length[allIdExprSR[n]],{n,12}]
  • PARI
    WeighT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v,n,(-1)^(n-1)/n))))-1,-#v)}
    seq(n)={my(v=[1]); for(n=2, n, my(t=WeighT(v)-v); v=concat(v, v[n-1] + sum(k=1, n-2, v[k]*t[n-k-1]))); v} \\ Andrew Howroyd, Aug 19 2018

Extensions

Terms a(13) and beyond from Andrew Howroyd, Aug 19 2018

A317655 Number of free pure symmetric multifunctions with leaves a multiset whose multiplicities are the integer partition with Heinz number n.

Original entry on oeis.org

0, 1, 1, 2, 3, 8, 10, 15, 50, 35, 37, 96, 144, 160, 299, 184, 589, 840, 2483, 578, 1729, 750, 10746, 1627, 2246, 3578, 9357, 3367, 47420, 6397, 212668, 3155, 9818, 17280, 15666, 18250, 966324, 84232, 54990, 12471, 4439540, 45015
Offset: 1

Views

Author

Gus Wiseman, Aug 03 2018

Keywords

Comments

The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
A free pure symmetric multifunction f in EPSM is either (case 1) a positive integer, or (case 2) an expression of the form h[g_1, ..., g_k] where k > 0, h is in EPSM, each of the g_i for i = 1, ..., k is in EPSM, and for i < j we have g_i <= g_j under a canonical total ordering of EPSM, such as the Mathematica ordering of expressions.

Examples

			The a(6) = 8 free pure symmetric multifunctions:
  1[1[2]]
  1[2[1]]
  2[1[1]]
  1[1][2]
  1[2][1]
  2[1][1]
  1[1,2]
  2[1,1]
		

Crossrefs

Programs

  • Mathematica
    sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
    mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
    exprUsing[m_]:=exprUsing[m]=If[Length[m]==0,{},If[Length[m]==1,{First[m]},Join@@Cases[Union[Table[PR[m[[s]],m[[Complement[Range[Length[m]],s]]]],{s,Take[Subsets[Range[Length[m]]],{2,-2}]}]],PR[h_,g_]:>Join@@Table[Apply@@@Tuples[{exprUsing[h],Union[Sort/@Tuples[exprUsing/@p]]}],{p,mps[g]}]]]];
    got[y_]:=Join@@Table[Table[i,{y[[i]]}],{i,Range[Length[y]]}];
    primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    Table[Length[exprUsing[got[Reverse[primeMS[n]]]]],{n,40}]

A317656 Number of free pure symmetric multifunctions whose leaves are the integer partition with Heinz number n.

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 3, 1, 2, 1, 8, 1, 2, 2, 10, 1, 8, 1, 8, 2, 2, 1, 35, 1, 2, 3, 8, 1, 15, 1, 37, 2, 2, 2, 50, 1, 2, 2, 35, 1, 15, 1, 8, 8, 2, 1, 160, 1, 8, 2, 8, 1, 35, 2, 35, 2, 2, 1, 96, 1, 2, 8, 144, 2, 15, 1, 8, 2, 15, 1, 299, 1, 2, 8, 8, 2, 15, 1, 160
Offset: 1

Views

Author

Gus Wiseman, Aug 03 2018

Keywords

Comments

A free pure symmetric multifunction f in EPSM is either (case 1) a positive integer, or (case 2) an expression of the form h[g_1, ..., g_k] where k > 0, h is in EPSM, each of the g_i for i = 1, ..., k is in EPSM, and for i < j we have g_i <= g_j under a canonical total ordering of EPSM, such as the Mathematica ordering of expressions.

Examples

			The a(12) = 8 free pure symmetric multifunctions are 1[1[2]], 1[2[1]], 1[1,2], 2[1[1]], 2[1,1], 1[1][2], 1[2][1], 2[1][1].
		

Crossrefs

Programs

  • Mathematica
    sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
    mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
    exprUsing[m_]:=exprUsing[m]=If[Length[m]==0,{},If[Length[m]==1,{First[m]},Join@@Cases[Union[Table[PR[m[[s]],m[[Complement[Range[Length[m]],s]]]],{s,Take[Subsets[Range[Length[m]]],{2,-2}]}]],PR[h_,g_]:>Join@@Table[Apply@@@Tuples[{exprUsing[h],Union[Sort/@Tuples[exprUsing/@p]]}],{p,mps[g]}]]]];
    primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    Table[Length[exprUsing[primeMS[n]]],{n,100}]

A259063 E.g.f.: Series_Reversion( 3*x - 2*x*exp(x) ).

Original entry on oeis.org

1, 4, 54, 1208, 37810, 1521252, 74800558, 4346473840, 291409650378, 22142153337500, 1880332153123270, 176486211108436968, 18142303135426278562, 2027140583610836224468, 244622970048028087152990, 31706140285613089502561504, 4392907300768938557656691194, 647905974466168686991684285836
Offset: 1

Views

Author

Paul D. Hanna, Jun 17 2015

Keywords

Examples

			E.g.f.: A(x) = x + 4*x^2/2! + 54*x^3/3! + 1208*x^4/4! + 37810*x^5/5! + ...
where A(3*x - 2*x*exp(x)) = x.
Also we have the related infinite series.
O.g.f.: F(x) = x + 4*x^2 + 54*x^3 + 1208*x^4 + 37810*x^5 + 1521252*x^6 + ...
where F(x)/x = 1/3 + 2/(3-x)^2 + 2^2/(3-2*x)^3 + 2^3/(3-3*x)^4 + 2^4/(3-4*x)^5 +...
		

Crossrefs

Programs

  • Mathematica
    Rest[CoefficientList[InverseSeries[Series[3*x - 2*x*E^x, {x, 0, 20}], x],x] * Range[0, 20]!] (* Vaclav Kotesovec, Jun 19 2015 *)
  • PARI
    {a(n) = local(A=x); A = serreverse(3*x - 2*x*exp(x +x*O(x^n) )); n!*polcoeff(A,n)}
    for(n=1,20,print1(a(n),", "))
    
  • PARI
    {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D}
    {a(n)=local(A=x); A = x + sum(m=1, n, Dx(m-1, 2^m*(exp(x+x*O(x^n))-1)^m * x^m/m!)); n!*polcoeff(A, n)}
    for(n=1, 25, print1(a(n), ", "))
    
  • PARI
    {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D}
    {a(n)=local(A=x+x^2+x*O(x^n)); A = x*exp(sum(m=1, n, Dx(m-1, 2^m*(exp(x+x*O(x^n))-1)^m * x^(m-1)/m!)+x*O(x^n))); n!*polcoeff(A, n)}
    for(n=1, 25, print1(a(n), ", "))

Formula

O.g.f.: x * Sum_{n>=0} 2^n / (3 - n*x)^(n+1).
E.g.f.: x + Sum_{n>=1} d^(n-1)/dx^(n-1) 2^n * (exp(x)-1)^n * x^n / n!.
E.g.f.: x*exp( Sum_{n>=1} d^(n-1)/dx^(n-1) 2^n * (exp(x)-1)^n * x^(n-1) / n! ).
a(n) ~ (c/(3*exp(1)))^n * n^(n-1) / (sqrt(c+1) * (c-1)^(2*n-1)), where c = LambertW(3*exp(1)/2). - Vaclav Kotesovec, Jun 19 2015

A259064 E.g.f.: Series_Reversion( 4*x - 3*x*exp(x) ).

Original entry on oeis.org

1, 6, 117, 3792, 172005, 10030248, 714843885, 60207412128, 5850995291397, 644410711219800, 79322681596610661, 10791841135527454896, 1608054016025580893445, 260445389091217967677992, 45557042043723212142506205, 8559094926999510089793332544, 1718950045690606262911636792677
Offset: 1

Views

Author

Paul D. Hanna, Jun 17 2015

Keywords

Examples

			E.g.f.: A(x) = x + 6*x^2/2! + 117*x^3/3! + 3792*x^4/4! + 172005*x^5/5! +...
where A(4*x - 3*x*exp(x)) = x.
Also we have the related infinite series.
O.g.f.: F(x) = x + 6*x^2 + 117*x^3 + 3792*x^4 + 172005*x^5 + 10030248*x^6 +...
where F(x)/x = 1/4 + 3/(4-x)^2 + 3^2/(4-2*x)^3 + 3^3/(4-3*x)^4 + 3^4/(4-4*x)^5 +...
		

Crossrefs

Programs

  • Mathematica
    Rest[CoefficientList[InverseSeries[Series[4*x - 3*x*E^x, {x, 0, 20}], x],x] * Range[0, 20]!] (* Vaclav Kotesovec, Jun 19 2015 *)
  • PARI
    {a(n) = local(A=x); A = serreverse(4*x - 3*x*exp(x +x*O(x^n) )); n!*polcoeff(A,n)}
    for(n=1,20,print1(a(n),", "))
    
  • PARI
    {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D}
    {a(n)=local(A=x); A=x+sum(m=1, n, Dx(m-1, 3^m*(exp(x+x*O(x^n))-1)^m*x^m/m!)); n!*polcoeff(A, n)}
    for(n=1, 25, print1(a(n), ", "))
    
  • PARI
    {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D}
    {a(n)=local(A=x+x^2+x*O(x^n)); A=x*exp(sum(m=1, n, Dx(m-1, 3^m*(exp(x+x*O(x^n))-1)^m*x^(m-1)/m!)+x*O(x^n))); n!*polcoeff(A, n)}
    for(n=1, 25, print1(a(n), ", "))

Formula

O.g.f.: x * Sum_{n>=0} 3^n / (4 - n*x)^(n+1).
E.g.f.: x + Sum_{n>=1} d^(n-1)/dx^(n-1) 3^n * (exp(x)-1)^n * x^n / n!.
E.g.f.: x*exp( Sum_{n>=1} d^(n-1)/dx^(n-1) 3^n * (exp(x)-1)^n * x^(n-1) / n! ).
a(n) ~ (c/(4*exp(1)))^n * n^(n-1) / (sqrt(c+1) * (c-1)^(2*n-1)), where c = LambertW(4*exp(1)/3). - Vaclav Kotesovec, Jun 19 2015

A262673 Number of pointed trees on normal pointed multisets of weight n.

Original entry on oeis.org

1, 3, 34, 615, 15410, 494018
Offset: 1

Views

Author

Gus Wiseman, Sep 26 2015

Keywords

Comments

A pointed multiset is normal if its entries span an initial interval of positive integers.

Examples

			The a(2) = 3 pointed trees are 1[1 1], 1[1 2], 2[1 2].
The a(3) = 34 pointed trees of the form rootpoint[pointedbranch ... pointedbranch] are:
1[1 1[1 1]], 1[1[1 1] 1], 1[1 1 1],
1[1 2[2 2]], 1[1[1 2] 2], 1[1 2 2],
2[1 2[2 2]], 2[1[1 2] 2], 2[2 2[1 2]], 2[2[1 2] 2], 2[1 2 2],
1[1 1[1 2]], 1[1 2[1 2]], 1[1[1 1] 2], 1[1[1 2] 1], 1[1 1 2],
2[1 2[1 2]], 2[1[1 1] 2], 2[1 1 2],
1[1 2[2 3]], 1[1 3[2 3]], 1[1[1 2] 3], 1[1[1 3] 2], 1[1 2 3],
2[1 2[2 3]], 2[1[1 3] 2], 2[2 3[1 3]], 2[2[1 2] 3], 2[1 2 3],
3[1 3[2 3]], 3[1[1 2] 3], 3[2 3[1 3]], 3[2[1 2] 3], 3[1 2 3].
		

Crossrefs

A300626 Number of inequivalent colorings of free pure symmetric multifunctions (with empty expressions allowed) with n positions.

Original entry on oeis.org

1, 1, 3, 11, 43, 187, 872, 4375, 23258, 130485, 767348, 4710715, 30070205, 198983975, 1361361925, 9607908808, 69812787049, 521377973359, 3996036977270, 31389624598631, 252408597286705, 2075472033455894, 17434190966525003, 149476993511444023, 1307022313790487959
Offset: 0

Views

Author

Gus Wiseman, Aug 17 2018

Keywords

Comments

A free pure symmetric multifunction (with empty expressions allowed) f in EOME is either (case 1) a positive integer, or (case 2) a possibly empty expression of the form h[g_1, ..., g_k] where k >= 0, h is in EOME, each of the g_i for i = 1, ..., k is in EOME, and for i < j we have g_i <= g_j under a canonical total ordering of EOME, such as the Mathematica ordering of expressions.
Also the number of inequivalent colorings of orderless Mathematica expressions with n positions.

Examples

			Inequivalent representatives of the a(3) = 11 colorings:
  1[1,1]  1[2,2]  1[1,2]  1[2,3]
  1[1[]]  1[2[]]
  1[][1]  1[][2]
  1[1][]  1[2][]
  1[][][]
		

Crossrefs

Programs

  • PARI
    \\ See links in A339645 for combinatorial species functions.
    cycleIndexSeries(n)={my(p=O(x)); for(n=1, n, p = x*sv(1) + x*p*sExp(p)); p}
    InequivalentColoringsSeq(cycleIndexSeries(15)) \\ Andrew Howroyd, Dec 30 2020

Extensions

Terms a(8) and beyond from Andrew Howroyd, Dec 30 2020

A317882 Number of free pure achiral multifunctions (with empty expressions allowed) with one atom and n positions.

Original entry on oeis.org

1, 1, 2, 5, 12, 31, 79, 211, 564, 1543, 4259, 11899, 33526, 95272, 272544, 784598, 2270888, 6604900, 19293793, 56581857, 166523462, 491674696, 1455996925, 4323328548, 12869353254, 38396655023, 114803257039, 343932660450, 1032266513328, 3103532577722
Offset: 1

Views

Author

Gus Wiseman, Aug 09 2018

Keywords

Comments

A free pure achiral multifunction (with empty expressions allowed) (AME) is either (case 1) the leaf symbol "o", or (case 2) a possibly empty expression of the form h[g, ..., g] where h and g are AMEs. The number of positions in an AME is the number of brackets [...] plus the number of o's.
Also the number of achiral Mathematica expressions with one atom and n positions.

Examples

			The a(5) = 12 AMEs:
  o[o[o]]
  o[o][o]
  o[o[][]]
  o[o,o,o]
  o[][o[]]
  o[][o,o]
  o[][][o]
  o[o[]][]
  o[o,o][]
  o[][o][]
  o[o][][]
  o[][][][]
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=If[n==1,1,Sum[a[k]*If[k==n-1,1,Sum[a[d],{d,Divisors[n-k-1]}]],{k,n-1}]];
    Array[a,12]
  • PARI
    seq(n)={my(p=O(x)); for(n=1, n, p = x + p*x*(1 + sum(k=1, n-2, subst(p + O(x^(n\k+1)), x, x^k)) ) + O(x*x^n)); Vec(p)} \\ Andrew Howroyd, Aug 19 2018
    
  • PARI
    seq(n)={my(v=vector(n)); v[1]=1; for(n=2, #v, v[n]=v[n-1] + sum(i=1, n-2, v[i]*sumdiv(n-i-1, d, v[d]))); v} \\ Andrew Howroyd, Aug 19 2018

Formula

a(1) = 1; a(n > 1) = a(n - 1) + Sum_{0 < k < n - 1} a(k) * Sum_{d|(n - k - 1)} a(d).

Extensions

Terms a(13) and beyond from Andrew Howroyd, Aug 19 2018

A317883 Number of free pure achiral multifunctions with one atom and n positions.

Original entry on oeis.org

1, 0, 1, 1, 3, 4, 10, 17, 37, 70, 150, 299, 634, 1311, 2786, 5879, 12584, 26904, 58005, 125242, 271819, 591297, 1290976, 2825170, 6199964, 13635749, 30057649, 66386206, 146903289, 325637240, 723024160, 1607805207, 3580476340, 7984266625, 17827226469
Offset: 1

Views

Author

Gus Wiseman, Aug 09 2018

Keywords

Comments

A free pure achiral multifunction (PAM) is either (case 1) the leaf symbol "o", or (case 2) a nonempty expression of the form h[g, ..., g] where h and g are PAMs. The number of positions in a PAM is the number of brackets [...] plus the number of o's.

Examples

			The a(7) = 10 PAMs:
  o[o[o[o]]]
  o[o[o][o]]
  o[o][o[o]]
  o[o[o]][o]
  o[o][o][o]
  o[o[o,o,o]]
  o[o][o,o,o]
  o[o,o][o,o]
  o[o,o,o][o]
  o[o,o,o,o,o]
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=If[n==1,1,Sum[a[k]*Sum[a[d],{d,Divisors[n-k-1]}],{k,n-2}]];
    Array[a,12]
  • PARI
    seq(n)={my(p=O(x)); for(n=1, n, p = x + p*x*sum(k=1, n-2, subst(p + O(x^(n\k+1)), x, x^k) ) + O(x*x^n)); Vec(p)} \\ Andrew Howroyd, Aug 19 2018
    
  • PARI
    seq(n)={my(v=vector(n)); v[1]=1; for(n=2, #v, v[n]=sum(i=1, n-2, v[i]*sumdiv(n-i-1, d, v[d]))); v} \\ Andrew Howroyd, Aug 19 2018

Formula

a(1) = 1; a(n > 1) = Sum_{0 < k < n - 1} a(k) * Sum_{d|(n - k - 1)} a(d).
G.f. A(x) satisfies: A(x) = x * (1 + A(x) * Sum_{k>=1} A(x^k)). - Ilya Gutkovskiy, May 03 2019

Extensions

Terms a(13) and beyond from Andrew Howroyd, Aug 19 2018

A317884 Number of series-reduced achiral free pure multifunctions (with empty expressions allowed) with one atom and n positions.

Original entry on oeis.org

1, 1, 1, 2, 4, 8, 14, 26, 47, 87, 160, 295, 540, 997, 1832, 3369, 6197, 11406, 20975, 38594, 70991, 130610, 240275, 442043, 813184, 1496053, 2752251, 5063319, 9314879, 17136632, 31526032, 57998423, 106699160, 196294065, 361120800, 664352454, 1222204958
Offset: 1

Views

Author

Gus Wiseman, Aug 09 2018

Keywords

Comments

A series-reduced achiral expression (SRAE) is either (case 1) the leaf symbol "o", or (case 2) a possibly empty but not unitary expression of the form h[g, ..., g], where h and g are SRAEs. The number of positions in an SRAE is the number of brackets [...] plus the number of o's.
Also the number of series-reduced achiral Mathematica expressions with one atom and n positions.

Examples

			The a(6) = 8 SRAEs:
  o[o,o,o,o]
  o[o[],o[]]
  o[][o,o,o]
  o[][][o,o]
  o[o,o,o][]
  o[][o,o][]
  o[o,o][][]
  o[][][][][]
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=1, 1, a(n-1)+add(a(j)*add(
          a(d), d=numtheory[divisors](n-j-1) minus {n-j-1}), j=1..n-1))
        end:
    seq(a(n), n=1..45);  # Alois P. Heinz, Sep 05 2018
  • Mathematica
    allAchExprSR[n_] := If[n == 1, {"o"}, Join @@ Cases[Table[PR[k, n - k - 1], {k, n - 1}], PR[h_, g_] :> Join @@ Table[Apply @@@ Tuples[{allAchExprSR[h], Select[Tuples[allAchExprSR /@ p], SameQ @@ # &]}], {p, If[g == 0, {{}}, Join @@ Permutations /@ Rest[IntegerPartitions[g]]]}]]]; Table[Length[allAchExprSR[n]], {n, 12}]
    (* Second program: *)
    a[n_] := a[n] = If[n == 1, 1, a[n-1] + Sum[a[j]*DivisorSum[
         n-j-1, If[# < n-j-1, a[#], 0]&], {j, 1, n-2}]];
    Array[a, 45] (* Jean-François Alcover, May 17 2021, after Alois P. Heinz *)
  • PARI
    seq(n)={my(p=O(x)); for(n=1, n, p = x + p*x*(1 + sum(k=2, n-2, subst(p + O(x^(n\k+1)), x, x^k)) ) + O(x*x^n)); Vec(p)} \\ Andrew Howroyd, Aug 19 2018
    
  • PARI
    seq(n)={my(v=vector(n)); v[1]=1; for(n=2, #v, v[n]=v[n-1] + sum(i=1, n-2, v[i]*sumdiv(n-i-1, d, if(dAndrew Howroyd, Aug 19 2018

Formula

a(1) = 1; a(n > 1) = a(n-1) + Sum_{0 < k < n-1} a(k) * Sum_{d|(n-k-1), d < n-k-1} a(d).

Extensions

Terms a(13) and beyond from Andrew Howroyd, Aug 19 2018
Previous Showing 11-20 of 30 results. Next