A119262 -id:A119262 - cp's OEIS frontend

A320221 Irregular triangle where T(n,k) is the number of unlabeled series-reduced rooted trees with n leaves in which every leaf is at height k, (n>=1, min(1,n-1) <= k <= log_2(n)).

1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 6, 1, 1, 7, 1, 1, 11, 4, 1, 13, 6, 1, 20, 16, 1, 23, 23, 1, 33, 46, 1, 40, 70, 1, 54, 127, 1, 1, 65, 189, 1, 1, 87, 320, 5, 1, 104, 476, 10, 1, 136, 771, 32, 1, 164, 1145, 63, 1, 209, 1795, 154, 1, 252, 2657, 304, 1, 319, 4091, 656

Offset: 1

Gus Wiseman, Oct 07 2018

			Triangle begins:
  1
  1
  1
  1  1
  1  1
  1  3
  1  3
  1  6  1
  1  7  1
  1 11  4
  1 13  6
  1 20 16
  1 23 23
  1 33 46
  1 40 70
The T(11,3) = 6 rooted trees:
   (((oo)(oo))((oo)(ooooo)))
   (((oo)(oo))((ooo)(oooo)))
   (((oo)(ooo))((oo)(oooo)))
   (((oo)(ooo))((ooo)(ooo)))
  (((oo)(oo))((oo)(oo)(ooo)))
  (((oo)(ooo))((oo)(oo)(oo)))

Andrew Howroyd, Table of n, a(n) for n = 1..1154 (rows 1..200)

Row sums are A120803. Second column is A083751. A regular version is A320179.
Cf. A000669, A005804, A048816, A119262, A120803, A141268, A244925, A319312.
Cf. A316624, A320154, A320155, A320160, A320172, A320173.

qurt[n_]:=If[n==1,{{}},Join@@Table[Union[Sort/@Tuples[qurt/@ptn]],{ptn,Select[IntegerPartitions[n],Length[#]>1&]}]];
DeleteCases[Table[Length[Select[qurt[n],SameQ[##,k]&@@Length/@Position[#,{}]&]],{n,10},{k,0,n-1}],0,{2}]

EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
T(n)={my(u=vector(n), v=vector(n), h=1); u[1]=1; while(u, v+=u*h; h*=x; u=EulerT(u)-u); v[1]=x; [Vecrev(p/x) | p<-v]}
{ my(A=T(15)); for(n=1, #A, print(A[n])) } \\ Andrew Howroyd, Dec 09 2020

Terms a(36) and beyond from Andrew Howroyd, Dec 09 2020

Name clarified by Andrew Howroyd, Dec 09 2020

A320266 Number of balanced orderless tree-factorizations of n.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 4, 1, 2, 2, 6, 1, 4, 1, 4, 2, 2, 1, 8, 2, 2, 3, 4, 1, 5, 1, 9, 2, 2, 2, 11, 1, 2, 2, 8, 1, 5, 1, 4, 4, 2, 1, 17, 2, 4, 2, 4, 1, 8, 2, 8, 2, 2, 1, 13, 1, 2, 4, 19, 2, 5, 1, 4, 2, 5, 1, 24, 1, 2, 4, 4, 2, 5, 1, 17, 6, 2, 1, 13, 2

Offset: 1

Gus Wiseman, Oct 08 2018

nonn

A rooted tree is balanced if all leaves are the same distance from the root.
An orderless tree-factorization of n is either (case 1) the number n itself or (case 2) a finite multiset of two or more orderless tree-factorizations, one of each factor in a factorization of n.
a(n) depends only on the prime signature of n. - Andrew Howroyd, Nov 18 2018

			The a(36) = 11 balanced orderless tree-factorizations:
  36,
  (2*18), (3*12), (4*9), (6*6),
  (2*2*9), (2*3*6), (3*3*4),
  (2*2*3*3), ((2*2)*(3*3)), ((2*3)*(2*3)).

Andrew Howroyd, Table of n, a(n) for n = 1..10000

Cf. A000669, A001055, A048816, A050336, A281118, A292505, A119262, A120803, A141268, A292504, A319312, A320160, A320267.

facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
oltfacs[n_]:=If[n<=1,{{}},Prepend[Union@@Function[q,Sort/@Tuples[oltfacs/@q]]/@DeleteCases[facs[n],{n}],n]];
Table[Length[Select[oltfacs[n],SameQ@@Length/@Position[#,_Integer]&]],{n,100}]

MultEulerT(u)={my(v=vector(#u)); v[1]=1; for(k=2, #u, forstep(j=#v\k*k, k, -k, my(i=j, e=0); while(i%k==0, i/=k; e++; v[j]+=binomial(e+u[k]-1, e)*v[i]))); v}
seq(n)={my(u=vector(n, i, 1), v=vector(n)); while(u, v+=u; u[1]=1; u=MultEulerT(u)-u); v} \\ Andrew Howroyd, Nov 18 2018

a(p^n) = A320160(n) for prime p. - Andrew Howroyd, Nov 18 2018

A320267 Number of balanced complete orderless tree-factorizations of n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 3, 1, 1, 1

Offset: 1

Gus Wiseman, Oct 08 2018

nonn

a(1) = 1 by convention.
A rooted tree is balanced if all leaves are the same distance from the root.
An orderless tree-factorization (see A292504 for definition) is complete if all leaves are prime numbers.
a(n) depends only on the prime signature of n. - Andrew Howroyd, Nov 18 2018

			The a(96) = 5 balanced complete orderless tree-factorizations:
     (2*2*2*2*2*3)
   ((2*2)*(2*2*2*3))
   ((2*3)*(2*2*2*2))
   ((2*2*2)*(2*2*3))
  ((2*2)*(2*2)*(2*3))

Andrew Howroyd, Table of n, a(n) for n = 1..10000

Cf. A001055, A048816, A050336, A281118, A292505, A119262, A120803, A292504, A320160, A320266.

facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
oltfacs[n_]:=If[n<=1,{{}},Prepend[Union@@Function[q,Sort/@Tuples[oltfacs/@q]]/@DeleteCases[facs[n],{n}],n]];
Table[Length[Select[oltfacs[n],And[SameQ@@Length/@Position[#,_Integer],FreeQ[#,_Integer?(!PrimeQ[#]&)]]&]],{n,100}]

MultEulerT(u)={my(v=vector(#u)); v[1]=1; for(k=2, #u, forstep(j=#v\k*k, k, -k, my(i=j, e=0); while(i%k==0, i/=k; e++; v[j]+=binomial(e+u[k]-1, e)*v[i]))); v}
seq(n)={my(u=vector(n, i, i==1 || isprime(i)), v=vector(n)); while(u, v+=u; u[1]=1; u=MultEulerT(u)-u); v} \\ Andrew Howroyd, Nov 18 2018

a(p^n) = A120803(n) for prime p. - Andrew Howroyd, Nov 18 2018

A131909 Triangle, read by rows, where T(n,k) = T(n-1,k-2) + T(n-1,k-1) for n>=k>1, with T(0,0)=1 and T(n,0) = T(n+1,1) = T(n-1,n-1) for n>0.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 1, 2, 3, 3, 2, 3, 3, 5, 5, 3, 5, 5, 6, 8, 8, 5, 8, 8, 10, 11, 14, 14, 8, 13, 13, 16, 18, 21, 25, 25, 14, 22, 21, 26, 29, 34, 39, 46, 46, 25, 39, 36, 43, 47, 55, 63, 73, 85, 85, 46, 71, 64, 75, 79, 90, 102, 118, 136, 158, 158, 85, 131, 117, 135, 139, 154, 169

Offset: 0

Paul D. Hanna, Jul 26 2007

A119262(n) is the number of B-trees of order infinity with n leaves.

			Triangle begins:
1;
1, 1;
1, 1, 2;
2, 1, 2, 3;
3, 2, 3, 3, 5;
5, 3, 5, 5, 6, 8;
8, 5, 8, 8, 10, 11, 14;
14, 8, 13, 13, 16, 18, 21, 25;
25, 14, 22, 21, 26, 29, 34, 39, 46;
46, 25, 39, 36, 43, 47, 55, 63, 73, 85;
85, 46, 71, 64, 75, 79, 90, 102, 118, 136, 158;
158, 85, 131, 117, 135, 139, 154, 169, 192, 220, 254, 294; ...
Illustrate T(n,k) = T(n-1,k-2) + T(n-1,k-1):
T(5,3) = T(4,1) + T(4,2) = 2 + 3 = 5;
T(6,4) = T(5,2) + T(5,3) = 5 + 5 = 10;
T(8,3) = T(7,1) + T(7,2) = 8 +13 = 21.

Cf. A119262 (columns 0, 1 and main diagonal); A131910 (central terms).

PARI
```
T(n,k)=if(k<0 || n
				
```

Row sums equal powers of 2. T(n,0) = A119262(n+1) for n>=0, where g.f. G(x) of A119262 satisfies: G(x) = x + G(x^2/(1-x)).

A352042 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/3)} binomial(n-2k-1,k) a(k).

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 4, 6, 9, 13, 19, 28, 41, 61, 93, 144, 226, 359, 574, 920, 1475, 2361, 3769, 6000, 9528, 15100, 23897, 37789, 59739, 94446, 149365, 236322, 374073, 592357, 938311, 1486625, 2355620, 3732704, 5914682, 9371599, 14847866, 23522460, 37262742, 59026662

Offset: 0

Ilya Gutkovskiy, Mar 01 2022

nonn

Cf. A119262, A352043.

a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 2 k - 1, k] a[k], {k, 0, Floor[(n - 1)/3]}]; Table[a[n], {n, 0, 43}]
nmax = 43; A[] = 0; Do[A[x] = 1 + x A[x^3/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]

G.f. A(x) satisfies: A(x) = 1 + x * A(x^3/(1 - x)) / (1 - x).

A352043 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-3k-1,k) a(k).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 3, 4, 5, 7, 10, 14, 19, 26, 36, 50, 69, 95, 131, 181, 250, 346, 482, 678, 963, 1380, 1994, 2903, 4252, 6254, 9222, 13616, 20109, 29681, 43755, 64394, 94583, 138632, 202755, 295906, 430986, 626585, 909500, 1318384, 1909042, 2762122, 3994290

Offset: 0

Ilya Gutkovskiy, Mar 01 2022

nonn

Cf. A119262, A352042.

a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 3 k - 1, k] a[k], {k, 0, Floor[(n - 1)/4]}]; Table[a[n], {n, 0, 46}]
nmax = 46; A[] = 0; Do[A[x] = 1 + x A[x^4/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]

G.f. A(x) satisfies: A(x) = 1 + x * A(x^4/(1 - x)) / (1 - x).

cp's OEIS Frontend

A320221 Irregular triangle where T(n,k) is the number of unlabeled series-reduced rooted trees with n leaves in which every leaf is at height k, (n>=1, min(1,n-1) <= k <= log_2(n)).

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A320266 Number of balanced orderless tree-factorizations of n.

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A320267 Number of balanced complete orderless tree-factorizations of n.

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A131909 Triangle, read by rows, where T(n,k) = T(n-1,k-2) + T(n-1,k-1) for n>=k>1, with T(0,0)=1 and T(n,0) = T(n+1,1) = T(n-1,n-1) for n>0.

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A352042 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/3)} binomial(n-2*k-1,k) * a(k).

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A352043 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-3*k-1,k) * a(k).

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Formula

A352042 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/3)} binomial(n-2k-1,k) a(k).

A352043 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-3k-1,k) a(k).