A022811 -id:A022811 - cp's OEIS frontend

A355383 Number of pairs (y, v), where y is a partition of n and v is a sub-multiset of y whose cardinality equals the number of distinct parts in y.

1, 1, 2, 3, 6, 10, 16, 26, 42, 64, 100, 150, 224, 330, 482, 697, 999, 1418, 1996, 2794, 3879, 5355, 7343, 10018, 13583, 18338, 24618, 32917, 43790, 58043, 76591, 100716, 131906, 172194, 223966, 290423, 375318, 483668, 621368, 796138, 1017146

Offset: 0

Gus Wiseman, Jul 02 2022

nonn

If a partition is regarded as an arrow from the number of parts to the number of distinct parts, this sequence counts composable containments of partitions.

			The a(0) = 1 through a(5) = 10 pairs:
  ()()  (1)(1)  (2)(2)   (3)(3)    (4)(4)     (5)(5)
                (11)(1)  (21)(21)  (31)(31)   (41)(41)
                         (111)(1)  (22)(2)    (32)(32)
                                   (211)(11)  (311)(11)
                                   (211)(21)  (311)(31)
                                   (1111)(1)  (221)(21)
                                              (221)(22)
                                              (2111)(11)
                                              (2111)(21)
                                              (11111)(1)

With multiplicity we have A339006.
The version for compositions is A355384.
The homogeneous version w/o containment is A355385, compositions A355388.
A001970 counts multiset partitions of partitions.
A063834 counts partitions of each part of a partition.
Splitting partitions: A072706, A316245, A317715, A318683, A318684, A319794, A323433, A323583, A336131-A336136.
Cf. A000009, A022811, A032020, A070933, A181591, A181819, A319910, A355382.

Table[Sum[Length[Union[Subsets[y,{Length[Union[y]]}]]],{y,IntegerPartitions[n]}],{n,0,15}]

A355385 Number of pairs (y, v) of integer partitions of n where the length of v equals the number of distinct parts in y.

Original entry on oeis.org

1, 1, 2, 3, 7, 12, 25, 43, 81, 141, 243, 409, 699, 1132, 1844, 2995, 4744, 7408, 11655, 17839, 27509, 41546, 62879, 93537, 139974, 205547, 302714, 440097, 640968, 921774, 1327538, 1891548, 2696635, 3809860, 5380257, 7540778, 10561566, 14687109, 20408170, 28183998, 38882009

Offset: 0

Gus Wiseman, Jul 02 2022

nonn

Also the number of composable pairs of integer partitions of n, where a partition is regarded as an arrow from (number of parts) to (number of distinct parts). Is there a nice choice of a composition operation making this into an associative category?

			The a(0) = 1 through a(5) = 10 pairs:
  ()()  (1)(1)  (2)(2)   (3)(3)    (4)(4)     (5)(5)
                (11)(2)  (21)(21)  (31)(31)   (41)(41)
                         (111)(3)  (31)(22)   (41)(32)
                                   (22)(4)    (32)(41)
                                   (211)(31)  (32)(32)
                                   (211)(22)  (311)(41)
                                   (1111)(4)  (311)(32)
                                              (221)(41)
                                              (221)(32)
                                              (2111)(41)
                                              (2111)(32)
                                              (11111)(5)

Andrew Howroyd, Table of n, a(n) for n = 0..1000

The inhomogeneous version with containment and multiplicity is A339006.
The inhomogeneous version with containment is A355383.
The inhomogeneous version with containment for compositions is A355384.
The version for compositions is A355388.
A001970 counts multiset partitions of partitions.
A063834 counts partitions of each part of a partition.
A323583 counts splittings of partitions.
Cf. A000009, A008284, A022811, A032020, A070933, A072706, A116608, A279787, A319910, A336135.

Table[Length[Select[Tuples[IntegerPartitions[n],2],Length[Union[#[[1]]]]==Length[#[[2]]]&]],{n,0,15}]

\\ P gives A008284 and R gives A116608 as g.f.'s.
P(n,y) = {1/prod(k=1, n, 1 - y*x^k + O(x*x^n))}
R(n,y) = {prod(k=1, n, 1 + y/(1 - x^k) - y + O(x*x^n))}
seq(n) = {my(g=Vec(P(n,y)), h=Vec(R(n,y))); vector(n+1, i, my(p=g[i], q=h[i]); sum(j=0, poldegree(q), polcoef(p,j)*polcoef(q,j)))} \\ Andrew Howroyd, Dec 31 2022

a(n) = Sum_{j >= 1} A116608(n,j) * A008284(n,j) for n > 0. - Andrew Howroyd, Dec 31 2022

Terms a(26) and beyond from Andrew Howroyd, Dec 31 2022

A022812 Number of terms in n-th derivative of a function composed with itself 4 times.

Original entry on oeis.org

1, 1, 4, 10, 26, 55, 121, 237, 468, 867, 1597, 2821, 4952, 8421, 14206, 23439, 38324, 61570, 98112, 154111, 240197, 370015, 565802, 856664, 1288366, 1921016, 2846572, 4186730, 6122369, 8893904, 12851713, 18460961, 26388354, 37519159, 53101687, 74792210

Offset: 0

Winston C. Yang (yang(AT)math.wisc.edu)

nonn

W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Alois P. Heinz, Table of n, a(n) for n = 0..1000
W. C. Yang, Derivatives are essentially integer partitions, Discrete Mathematics, 222(1-3), July 2000, 235-245.

Cf. A008778, A022811-A022818, A024207-A024210. First column of A039806.

b[n_, i_, k_] := b[n, i, k] = If[n < k, 0, If[n == 0, 1, If[i < 1, 0, Sum[b[n - i*j, i - 1, k - j], {j, 0, Min[n/i, k]}]]]];
a[n_, k_] := a[n, k] = If[k == 1, 1, Sum[b[n, n, i]*a[i, k-1], {i, 0, n}]];
a[n_] := a[n, 4]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A022813 Number of terms in n-th derivative of a function composed with itself 5 times.

Original entry on oeis.org

1, 1, 5, 15, 45, 110, 271, 599, 1309, 2690, 5436, 10545, 20148, 37341, 68223, 121878, 214846, 371993, 636570, 1073325, 1790721, 2950922, 4816603, 7778937, 12455988, 19761148, 31108121, 48572686, 75307513, 115909727, 177255526, 269294119, 406708721, 610593948

Offset: 0

Winston C. Yang (yang(AT)math.wisc.edu)

nonn

W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Alois P. Heinz, Table of n, a(n) for n = 0..1000
W. C. Yang, Derivatives are essentially integer partitions, Discrete Mathematics, 222(1-3), July 2000, 235-245.

Cf. A008778, A022811-A022818, A024207-A024210. First column of A039807.

b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A355388 Number of composable pairs (y, v) of integer compositions of n, where a composition is regarded as an arrow from the number of parts to the number of distinct parts.

Original entry on oeis.org

1, 1, 2, 6, 18, 58, 174, 536, 1656, 4947, 14800, 43157, 126572, 364070, 1039926, 2938898, 8223400, 22846370, 62930113, 172177400, 467002792, 1259736804, 3371190792, 8973530491, 23728305128, 62421018163, 163255839779, 424842462529, 1100006243934, 2834558927244, 7270915592897

Offset: 0

Gus Wiseman, Jul 02 2022

nonn

Being composable here means that the length of v equals the number of distinct parts in y.

			The a(0) = 1 through a(4) = 18 pairs:
  ()()  (1)(1)  (2)(2)   (3)(3)    (4)(4)
                (11)(2)  (21)(21)  (31)(31)
                         (21)(12)  (31)(13)
                         (12)(21)  (31)(22)
                         (12)(12)  (13)(31)
                         (111)(3)  (13)(13)
                                   (13)(22)
                                   (22)(4)
                                   (211)(31)
                                   (211)(13)
                                   (211)(22)
                                   (121)(31)
                                   (121)(13)
                                   (121)(22)
                                   (112)(31)
                                   (112)(13)
                                   (112)(22)
                                   (1111)(4)

Alois P. Heinz, Table of n, a(n) for n = 0..800 (first 201 terms from Andrew Howroyd)

The case with containment is A032020.
The inhomogeneous version with containment is A355384, partitions A355383.
The version for partitions is A355385, with containment A000009.
A133494 counts compositions of each part of a composition, strict A336139.
A323583 counts splittings of partitions.
Cf. A001970, A022811, A063834, A070933, A316245, A319910, A355382.

b:= proc(n, i, p) option remember; `if`(n=0, p!, `if`(i<1, 0,
      expand(add(b(n-i*j, i-1, p+j)/j!*`if`(j=0, 1, x), j=0..n/i))))
    end:
a:= n-> (p-> add(coeff(p, x, i)*binomial(n-1, i-1), i=0..degree(p)))(b(n$2, 0)):
seq(a(n), n=0..30);  # Alois P. Heinz, Jan 01 2023

Table[Length[Select[Tuples[Join@@Permutations/@IntegerPartitions[n],2], Length[Union[#[[1]]]]==Length[#[[2]]]&]],{n,0,10}]

a(n) = {if(n==0, 1, my(s=0); forpart(p=n, p=Vec(p); my(S=Set(p)); s += binomial(n-1, #S-1)*(#p)!/prod(i=1, #S, my(c=#select(t->t==S[i], p)); c! )); s)} \\ Andrew Howroyd, Jan 01 2023

\\ for larger n.
a(n) = { local(Cache=Map());
  my(F(r,m,p,q) = my(key=[r,m,p,q], z); if(!mapisdefined(Cache, key, &z),
  z = if(m==0, if(r==0, p!*binomial(n-1, q-1)), self()(r, m-1, p, q) + sum(j=1, r\m, self()(r-j*m, min(m-1, r-j*m), p+j, q+1)/j!));
  mapput(Cache, key, z) ); z);
  if(n==0, 1, F(n, n, 0, 0))
} \\ Andrew Howroyd, Jan 01 2023

a(n) = Sum_{k>=1} binomial(n-1, k-1)*A235998(n, k) for n > 0. - Andrew Howroyd, Jan 01 2023

Terms a(14) and beyond from Andrew Howroyd, Jan 01 2023

A022814 Number of terms in n-th derivative of a function composed with itself 6 times.

Original entry on oeis.org

1, 1, 6, 21, 71, 196, 532, 1301, 3101, 6956, 15217, 31951, 65670, 130914, 256150, 489690, 920905, 1699693, 3092751, 5540571, 9802091, 17114237, 29550346, 50444952, 85264328, 142682505, 236649524, 389033014, 634408230, 1026350152, 1648328017, 2628254619

Offset: 0

Winston C. Yang (yang(AT)math.wisc.edu)

nonn

W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Alois P. Heinz, Table of n, a(n) for n = 0..1000
W. C. Yang, Derivatives are essentially integer partitions, Discrete Mathematics, 222(1-3), July 2000, 235-245.

Cf. A008778, A022811-A022818, A024207-A024210. First column of A050300.

b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A022815 Number of terms in 5th derivative of a function composed with itself n times.

Original entry on oeis.org

1, 7, 23, 55, 110, 196, 322, 498, 735, 1045, 1441, 1937, 2548, 3290, 4180, 5236, 6477, 7923, 9595, 11515, 13706, 16192, 18998, 22150, 25675, 29601, 33957, 38773, 44080, 49910, 56296, 63272, 70873, 79135, 88095, 97791, 108262, 119548, 131690

Offset: 1

N. J. A. Sloane

			a(7) = 7*28 + (7*0+6*1+5*3+4*6+3*10+2*15+1*21) = 322. [_Bruno Berselli_, Jun 22 2013]

W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Vincenzo Librandi, Table of n, a(n) for n = 1..10000
W. C. Yang, Derivatives are essentially integer partitions, Discrete Mathematics, 222(1-3), July 2000, 235-245.

Cf. A008778, A022811-A022818, A024207-A024210.

[n*(n+1)*(n^2+13*n-2)/24: n in [1..40]]; // Vincenzo Librandi, Oct 10 2011

a(n) = n*(n+1)*(n^2+13*n-2)/24. - John W. Layman, Apr 27 2000
G.f.: x*(1-2*x^2+2*x)/(1-x)^5. [Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009]
a(n) = n*A000217(n) + sum((n-i)*A000217(i), i=0..n-1). [Bruno Berselli, Jun 23 2013]

G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.

More terms from Christian G. Bower, Aug 15 1999.

A024208 Number of terms in n-th derivative of a function composed with itself 8 times.

Original entry on oeis.org

1, 1, 8, 36, 148, 498, 1590, 4586, 12644, 32775, 81901, 196085, 455772, 1025779, 2252674, 4823546, 10116553, 20783490, 41949270, 83211931, 162552093, 312850854, 594086542, 1113610526, 2062796698, 3777567977, 6844786250, 12276620372, 21809737429, 38391720375

Offset: 0

Winston C. Yang (yang(AT)math.wisc.edu)

nonn

W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Alois P. Heinz, Table of n, a(n) for n = 0..1000
W. C. Yang, Derivatives are essentially integer partitions, Discrete Mathematics, 222(1-3), July 2000, 235-245.

Cf. A008778, A022811-A022817, A024207-A024210. First column of A050302.

Column k=8 of A022818.

b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A024209 Number of terms in n-th derivative of a function composed with itself 9 times.

Original entry on oeis.org

1, 1, 9, 45, 201, 735, 2517, 7785, 22857, 63024, 166819, 422537, 1035971, 2456694, 5672347, 12756334, 28053280, 60371967, 127479247, 264311585, 539102751, 1082474167, 2142579168, 4183251750, 8064722973, 15360809911, 28928858208, 53896616704, 99398216733

Offset: 0

Winston C. Yang (yang(AT)math.wisc.edu)

nonn

W. C. Yang (yang(AT)math.wisc.edu), Derivatives of self-compositions of functions, preprint, 1997.

Alois P. Heinz, Table of n, a(n) for n = 0..1000
W. C. Yang, Derivatives are essentially integer partitions, Discrete Mathematics, 222(1-3), July 2000, 235-245.

Cf. A008778, A022811-A022817, A024207-A024210. First column of A050303.

Column k=9 of A022818.

b[n_, i_, k_] := b[n, i, k] = If[nJean-François Alcover, Apr 28 2017, after Alois P. Heinz *)

If a(n,m) = number of terms in m-derivative of a function composed with itself n times, p(n,k) = number of partitions of n into k parts, then a(n,m) = sum_{i=0..m} p(m,i)*a(n-1,i).

A355382 Number of divisors d of n such that bigomega(d) = omega(n).

Original entry on oeis.org

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

Offset: 1

Gus Wiseman, Jul 02 2022

nonn

The statistic omega = A001221 counts distinct prime factors (without multiplicity).
The statistic bigomega = A001222 counts prime factors with multiplicity.
If positive integers are regarded as arrows from the number of prime factors to the number of distinct prime factors, this sequence counts divisible composable pairs. Is there a nice choice of a composition operation making this into an associative category?

			The set of divisors of 180 satisfying the condition is {12, 18, 20, 30, 45}, so a(180) = 5.

The version with multiplicity is A181591.
For partitions we have A355383, with multiplicity A339006.
The version for compositions is A355384.
Positions of first appearances are A355386.
A000005 counts divisors.
A001221 counts prime indices without multiplicity.
A001222 count prime indices with multiplicity.
A070175 gives representatives for bigomega and omega, triangle A303555.
Cf. A000712, A022811, A056239, A071625, A118914, A133494, A181819, A182850, A323014, A323022, A323023, A355385, A355388.

Table[Length[Select[Divisors[n],PrimeOmega[#]==PrimeNu[n]&]],{n,100}]

cp's OEIS Frontend

A355383 Number of pairs (y, v), where y is a partition of n and v is a sub-multiset of y whose cardinality equals the number of distinct parts in y.

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A355385 Number of pairs (y, v) of integer partitions of n where the length of v equals the number of distinct parts in y.

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A022812 Number of terms in n-th derivative of a function composed with itself 4 times.

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A022813 Number of terms in n-th derivative of a function composed with itself 5 times.

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A355388 Number of composable pairs (y, v) of integer compositions of n, where a composition is regarded as an arrow from the number of parts to the number of distinct parts.

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Maple

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A022814 Number of terms in n-th derivative of a function composed with itself 6 times.

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A022815 Number of terms in 5th derivative of a function composed with itself n times.

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Magma

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