A109092
Number of hierarchical orderings for n labeled elements with 2 possible classes A and B for levels l>=2. Labeled analog of A104460.
Original entry on oeis.org
1, 6, 53, 619, 8972, 155067, 3109269, 70893872, 1810283331, 51151579619, 1583934062306, 53322541667501, 1938521128765093, 75673000809822670, 3156390306304019025, 140076451219218605087, 6589244960448222899044, 327461842184597424792623, 17141751726301435708168665
Offset: 1
Let | denote a separator among different hierarchies of the hierarchical ordering. Let : denote a separator between levels in a hierarchy.
Furthermore, let a[1], a[2],... denote labeled elements.
An element a[i] will be written as a[i,A] if it falls into class A and as a[i,B] if it falls into class B. Note that at level l=1 no classes appear.
Then a(2) = 6 because a[1]a[2], a[1]|a[2], a[1]:a[2,A], a[2]:a[1,A], a[1]:a[2,B], a[2]:a[1,B].
- Alois P. Heinz, Table of n, a(n) for n = 1..140
- Robert Gill, The number of elements in a generalized partition semilattice, Discrete mathematics 186.1-3 (1998): 125-134. See Example 2.
- Norihiro Nakashima, Shuhei Tsujie, Enumeration of Flats of the Extended Catalan and Shi Arrangements with Species, arXiv:1904.09748 [math.CO], 2019.
- N. J. A. Sloane and Thomas Wieder, The Number of Hierarchical Orderings, arXiv:math/0307064 [math.CO], 2003; Order 21 (2004), 83-89.
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with(combstruct): A109092 := [T, {T=Set(Sequence(S,card>=1)), S=Sequence(U,card>=1), U=Set(Z,card>=1)},labeled]; seq(count(A109092, size=j), j=1..20);
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With[{nn=20},CoefficientList[Series[Exp[-(Exp[x]-1)/(-3+2Exp[x])],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Sep 16 2016 *)
A343349
Expansion of Product_{k>=1} 1 / (1 - x^k)^(4^(k-1)).
Original entry on oeis.org
1, 1, 5, 21, 95, 415, 1851, 8155, 36030, 158510, 696502, 3052966, 13359230, 58346206, 254405630, 1107479694, 4813850699, 20894227355, 90567536543, 392066476815, 1695180397145, 7320927664713, 31581573600685, 136094434672509, 585876330191950, 2519701493092958
Offset: 0
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a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*4^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..25); # Alois P. Heinz, Apr 12 2021
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nmax = 25; CoefficientList[Series[Product[1/(1 - x^k)^(4^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 4^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 25}]
A343350
Expansion of Product_{k>=1} 1 / (1 - x^k)^(5^(k-1)).
Original entry on oeis.org
1, 1, 6, 31, 171, 921, 5031, 27281, 148101, 801901, 4336902, 23415777, 126254962, 679805112, 3655679442, 19634501447, 105334380517, 564471596667, 3021754455157, 16160029793032, 86339725851558, 460874548444683, 2457961986888773, 13097958657023523, 69740119667456018
Offset: 0
-
a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*5^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..24); # Alois P. Heinz, Apr 12 2021
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nmax = 24; CoefficientList[Series[Product[1/(1 - x^k)^(5^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 5^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 24}]
A343351
Expansion of Product_{k>=1} 1 / (1 - x^k)^(6^(k-1)).
Original entry on oeis.org
1, 1, 7, 43, 280, 1792, 11586, 74550, 479892, 3083640, 19794678, 126908502, 812761299, 5199586119, 33230586285, 212172173565, 1353444677529, 8626044781761, 54931168743703, 349524243121795, 2222294161109422, 14119034725444774, 89639674321304392, 568720801952770012
Offset: 0
-
a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*6^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..23); # Alois P. Heinz, Apr 12 2021
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nmax = 23; CoefficientList[Series[Product[1/(1 - x^k)^(6^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 6^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 23}]
A343352
Expansion of Product_{k>=1} 1 / (1 - x^k)^(7^(k-1)).
Original entry on oeis.org
1, 1, 8, 57, 428, 3172, 23689, 176324, 1312550, 9757798, 72480269, 537854094, 3987751860, 29540543908, 218652961074, 1617159619805, 11951595353413, 88264810625245, 651404299886762, 4804261815210433, 35410065096578748, 260832137791524693, 1920169120639498017, 14127684273966098698
Offset: 0
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a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*7^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..23); # Alois P. Heinz, Apr 12 2021
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nmax = 23; CoefficientList[Series[Product[1/(1 - x^k)^(7^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 7^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 23}]
A343353
Expansion of Product_{k>=1} 1 / (1 - x^k)^(8^(k-1)).
Original entry on oeis.org
1, 1, 9, 73, 621, 5229, 44293, 374277, 3162447, 26694159, 225163687, 1897751079, 15983278059, 134519816427, 1131395821587, 9509592524371, 79880259426102, 670590654977718, 5626336598011078, 47179486350900358, 395410837699366686, 3312225325409475038, 27731588831310844302
Offset: 0
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a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*8^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..22); # Alois P. Heinz, Apr 12 2021
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nmax = 22; CoefficientList[Series[Product[1/(1 - x^k)^(8^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 8^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 22}]
A343354
Expansion of Product_{k>=1} 1 / (1 - x^k)^(9^(k-1)).
Original entry on oeis.org
1, 1, 10, 91, 865, 8155, 77251, 730435, 6905560, 65233120, 615847378, 5810270782, 54784324495, 516250199827, 4862041512625, 45765734635702, 430560567351208, 4048630897384450, 38051334554031551, 357459295903931045, 3356488167698692226, 31503001136703776561
Offset: 0
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a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*9^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..21); # Alois P. Heinz, Apr 12 2021
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nmax = 21; CoefficientList[Series[Product[1/(1 - x^k)^(9^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 9^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 21}]
A343355
Expansion of Product_{k>=1} 1 / (1 - x^k)^(10^(k-1)).
Original entry on oeis.org
1, 1, 11, 111, 1166, 12166, 127436, 1332936, 13939651, 145683351, 1521743103, 15886781603, 165770328383, 1728861822083, 18022063489023, 187778810866043, 1955660195168328, 20358764860253028, 211849198103034998, 2203562708619192998, 22911457758236641451, 238129937419462634151
Offset: 0
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a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
d*10^(d-1), d=numtheory[divisors](j)), j=1..n)/n)
end:
seq(a(n), n=0..21); # Alois P. Heinz, Apr 12 2021
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nmax = 21; CoefficientList[Series[Product[1/(1 - x^k)^(10^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[d 10^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 21}]
A343360
Expansion of Product_{k>=1} (1 + x^k)^(3^(k-1)).
Original entry on oeis.org
1, 1, 3, 12, 39, 138, 469, 1603, 5427, 18372, 61869, 207909, 696537, 2328039, 7762266, 25826142, 85749969, 284171598, 940027872, 3104280885, 10234808334, 33692547249, 110753171784, 363561071175, 1191860487561, 3902350627434, 12761565487173, 41685086306917, 136012008938158
Offset: 0
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h:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1)*binomial(3^(i-1), j), j=0..n/i)))
end:
a:= n-> h(n$2):
seq(a(n), n=0..28); # Alois P. Heinz, Apr 12 2021
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nmax = 28; CoefficientList[Series[Product[(1 + x^k)^(3^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 3^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 28}]
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seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(3^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
A104500
Number of different groupings among the hierarchical orderings of n unlabeled elements.
Original entry on oeis.org
1, 4, 11, 35, 98, 294, 832, 2401, 6774, 19137, 53466, 148994, 412233, 1136383, 3116654, 8515706, 23172455, 62836916, 169801824, 457406173, 1228382159, 3289493887, 8784935160, 23400668297, 62179339101, 164832960183, 435978612329, 1150673925933, 3030701471118
Offset: 1
Let * denote an element, let : denote separator among different levels within a hierarchy, let | denote a separator between different hierarchies. Furthermore, the braces {} indicate a group. For n=3 one has a(3) = 11 because
{***}, {*|*|*}, {*}{*}{*}, {*:*:*}, {*:**}, {*|**}, {*:*|*}, {*:*}{*}, {*|*}{*}, {**:*}, {*}{**}.
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etr:= proc(p) local b; b:=proc(n) option remember; `if`(n=0, 1, add(add(d*p(d), d=numtheory[divisors](j)) *b(n-j), j=1..n)/n) end end: b:= etr(n-> 2^(n-1)): a:= etr(b): seq(a(n), n=1..30); # Alois P. Heinz, Apr 21 2012
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etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[ j]}]*b[n-j], {j, 1, n}]/n]; b]; b = etr[Function[{n}, 2^(n-1)]]; a = etr[b]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Mar 05 2015, after Alois P. Heinz *)
Showing 1-10 of 12 results.
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