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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A290356 The seventh Euler transform of the sequence with g.f. 1+x.

Original entry on oeis.org

1, 1, 7, 28, 140, 602, 2772, 12166, 54046, 236093, 1030101, 4458247, 19223202, 82448782, 352247250, 1498724840, 6353940527, 26844401919, 113051495750, 474652297902, 1987159118837, 8296760311018, 34551340915438, 143533939056129, 594877730354756
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Comments

Also the number of 7-level rooted trees with n leaves. All n leaves are in level 7.

Crossrefs

Column k=7 of A290353.
Cf. A290355.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n<2, 1, `if`(k=0, 0, add(
          add(b(d, k-1)*d, d=divisors(j))*b(n-j, k), j=1..n)/n))
        end:
    a:= n-> b(n, 7):
    seq(a(n), n=0..30);
  • Mathematica
    b[n_, k_]:=b[n, k]=If[n<2, 1, If[k==0, 0, Sum[Sum[b[d, k - 1]*d, {d, Divisors[j]}] b[n - j, k], {j, n}]/n]]; Table[b[n, 7], {n, 0, 30}] (* Indranil Ghosh, Jul 30 2017, after Maple code *)

Formula

G.f.: Product_{j>0} 1/(1-x^j)^A290355(j).

A290357 The eighth Euler transform of the sequence with g.f. 1+x.

Original entry on oeis.org

1, 1, 8, 36, 204, 1002, 5244, 26328, 133476, 667335, 3331117, 16516607, 81607176, 401407499, 1967534543, 9609826869, 46788348316, 227114265649, 1099339308308, 5307155062783, 25556511343601, 122773840789344, 588473630650319, 2814565652799711, 13433897987956859
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Comments

Also the number of 8-level rooted trees with n leaves. All n leaves are in level 8.

Crossrefs

Column k=8 of A290353.
Cf. A290356.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n<2, 1, `if`(k=0, 0, add(
          add(b(d, k-1)*d, d=divisors(j))*b(n-j, k), j=1..n)/n))
        end:
    a:= n-> b(n, 8):
    seq(a(n), n=0..30);
  • Mathematica
    b[n_, k_]:=b[n, k]=If[n<2, 1, If[k==0, 0, Sum[Sum[b[d, k - 1]*d, {d, Divisors[j]}] b[n - j, k], {j, n}]/n]]; Table[b[n, 8], {n, 0, 30}] (* Indranil Ghosh, Jul 30 2017, after Maple code *)

Formula

G.f.: Product_{j>0} 1/(1-x^j)^A290356(j).

A290358 The ninth Euler transform of the sequence with g.f. 1+x.

Original entry on oeis.org

1, 1, 9, 45, 285, 1575, 9237, 52221, 297633, 1676364, 9425128, 52688379, 293582296, 1629482947, 9015732880, 49727160669, 273504111761, 1500271605182, 8209029290412, 44811239964075, 244069307558722, 1326536980923855, 7195340066129605, 38953817605037254
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Comments

Also the number of 9-level rooted trees with n leaves. All n leaves are in level 9.

Crossrefs

Column k=9 of A290353.
Cf. A290357.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n<2, 1, `if`(k=0, 0, add(
          add(b(d, k-1)*d, d=divisors(j))*b(n-j, k), j=1..n)/n))
        end:
    a:= n-> b(n, 9):
    seq(a(n), n=0..30);
  • Mathematica
    b[n_, k_]:=b[n, k]=If[n<2, 1, If[k==0, 0, Sum[Sum[b[d, k - 1]*d, {d, Divisors[j]}] b[n - j, k], {j, n}]/n]]; Table[b[n, 9], {n, 0, 30}] (* Indranil Ghosh, Jul 30 2017, after Maple code *)

Formula

G.f.: Product_{j>0} 1/(1-x^j)^A290357(j).

A323719 Array read by antidiagonals upwards where A(n, k) is the number of orderless factorizations of n with k - 1 levels of parentheses.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 4, 1, 1, 1, 1, 1, 3, 1, 5, 1, 1, 1, 1, 3, 1, 4, 1, 6, 1, 1, 1, 1, 2, 6, 1, 5, 1, 7, 1, 1, 1, 1, 2, 3, 10, 1, 6, 1, 8, 1, 1, 1, 1, 1, 3, 4, 15, 1, 7, 1, 9, 1, 1, 1, 1, 4, 1, 4, 5, 21, 1, 8, 1, 10, 1, 1, 1
Offset: 1

Views

Author

Gus Wiseman, Jan 25 2019

Keywords

Comments

An orderless factorization of n with k > 1 levels of parentheses is any multiset partition of an orderless factorization of n with k - 1 levels of parentheses. If k = 1 it is just an orderless factorization of n into factors > 1.

Examples

			Array begins:
       k=0  k=1  k=2  k=3  k=4  k=5  k=6  k=7  k=8  k=9  k=10 k=11 k=12
   n=1: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=2: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=3: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=4: 1    2    3    4    5    6    7    8    9   10   11   12   13
   n=5: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=6: 1    2    3    4    5    6    7    8    9   10   11   12   13
   n=7: 1    1    1    1    1    1    1    1    1    1    1    1    1
   n=8: 1    3    6   10   15   21   28   36   45   55   66   78   91
   n=9: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=10: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=11: 1    1    1    1    1    1    1    1    1    1    1    1    1
  n=12: 1    4    9   16   25   36   49   64   81  100  121  144  169
  n=13: 1    1    1    1    1    1    1    1    1    1    1    1    1
  n=14: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=15: 1    2    3    4    5    6    7    8    9   10   11   12   13
  n=16: 1    5   14   30   55   91  140  204  285  385  506  650  819
  n=17: 1    1    1    1    1    1    1    1    1    1    1    1    1
  n=18: 1    4    9   16   25   36   49   64   81  100  121  144  169
The A(12,3) = 16 orderless factorizations of 12 with 2 levels of parentheses:
  ((2*2*3))          ((2*6))      ((3*4))      ((12))
  ((2)*(2*3))        ((2)*(6))    ((3)*(4))
  ((3)*(2*2))        ((2))*((6))  ((3))*((4))
  ((2))*((2*3))
  ((2)*(2)*(3))
  ((3))*((2*2))
  ((2))*((2)*(3))
  ((3))*((2)*(2))
  ((2))*((2))*((3))
		

Crossrefs

Programs

  • Mathematica
    facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
    lev[n_,k_]:=If[k==0,{n},Join@@Table[Union[Sort/@Tuples[lev[#,k-1]&/@fac]],{fac,facs[n]}]];
    Table[Length[lev[sum-k,k]],{sum,12},{k,0,sum-1}]

A007715 Number of 5-leaf rooted trees with n levels.

Original entry on oeis.org

1, 7, 27, 75, 170, 336, 602, 1002, 1575, 2365, 3421, 4797, 6552, 8750, 11460, 14756, 18717, 23427, 28975, 35455, 42966, 51612, 61502, 72750, 85475, 99801, 115857, 133777, 153700, 175770, 200136, 226952, 256377, 288575, 323715, 361971, 403522, 448552, 497250
Offset: 1

Views

Author

Keywords

Examples

			a(7) = 7*28 - (7*0+4*1+1*3-2*6-5*10-8*15-11*21) = 602. - _Bruno Berselli_, Jun 22 2013
		

Crossrefs

Row n=5 of A290353.

Programs

  • Magma
    [n*(n+1)*(5*n^2+n+6)/24: n in [1..45]]; // Vincenzo Librandi, Jul 21 2011
  • Mathematica
    Table[n(n+1)(5n^2+n+6)/24,{n,40}] (* or *) LinearRecurrence[ {5,-10,10,-5,1},{1,7,27,75,170},40] (* Harvey P. Dale, Jul 20 2011 *)

Formula

Expansion of x*(1+2x+2x^2)/(1-x)^5.
a(n) = n*(n+1)*(5*n^2+n+6)/24. - T. D. Noe, Feb 09 2007
a(1)=1, a(2)=7, a(3)=27, a(4)=75, a(5)=170, a(n)=5*a(n-1)- 10*a(n-2)+ 10*a(n-3)-5*a(n-4)+a(n-5). - Harvey P. Dale, Jul 20 2011
a(n) = n*A000217(n) - sum((n-3*i)*A000217(i), i=0..n-1). - Bruno Berselli, Jun 22 2013

A290359 The tenth Euler transform of the sequence with g.f. 1+x.

Original entry on oeis.org

1, 1, 10, 55, 385, 2365, 15367, 96613, 611644, 3832477, 23970089, 149170604, 925530638, 5722654098, 35282873191, 216928671076, 1330360845060, 8139139896353, 49683631194244, 302640125458942, 1839793530751731, 11163107720200726, 67610680329079976
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Comments

Also the number of 10-level rooted trees with n leaves. All n leaves are in level 10.

Crossrefs

Column k=10 of A290353.
Cf. A290358.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n<2, 1, `if`(k=0, 0, add(
          add(b(d, k-1)*d, d=divisors(j))*b(n-j, k), j=1..n)/n))
        end:
    a:= n-> b(n, 10):
    seq(a(n), n=0..30);
  • Mathematica
    b[n_, k_]:=b[n, k]=If[n<2, 1, If[k==0, 0, Sum[Sum[b[d, k - 1]*d, {d, Divisors[j]}] b[n - j, k], {j, n}]/n]]; Table[b[n, 10], {n, 0, 30}] (* Indranil Ghosh, Jul 30 2017 *)

Formula

G.f.: Product_{j>0} 1/(1-x^j)^A290358(j).

A290360 Number of 6-leaf rooted trees with n levels.

Original entry on oeis.org

0, 1, 11, 58, 206, 571, 1337, 2772, 5244, 9237, 15367, 24398, 37258, 55055, 79093, 110888, 152184, 204969, 271491, 354274, 456134, 580195, 729905, 909052, 1121780, 1372605, 1666431, 2008566, 2404738, 2861111, 3384301, 3981392, 4659952, 5428049, 6294267
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Crossrefs

Row n=6 of A290353.

Programs

  • Maple
    a:= n-> ((((4*n+5)*n+10)*n+10)*n+1)*n/30:
    seq(a(n), n=0..40);
  • Mathematica
    LinearRecurrence[{6,-15,20,-15,6,-1},{0,1,11,58,206,571},40] (* Harvey P. Dale, Aug 22 2019 *)

Formula

G.f.: (3*x+1)*(x+1)^2*x / (x-1)^6.
a(n) = (4*n^5+5*n^4+10*n^3+10*n^2+n)/30.

A290361 Number of 7-leaf rooted trees with n levels.

Original entry on oeis.org

0, 1, 15, 111, 518, 1789, 5026, 12166, 26328, 52221, 96613, 168861, 281502, 450905, 697984, 1048972, 1536256, 2199273, 3085467, 4251307, 5763366, 7699461, 10149854, 13218514, 17024440, 21703045, 27407601, 34310745, 42606046, 52509633, 64261884, 78129176
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Crossrefs

Row n=7 of A290353.

Programs

  • Maple
    a:= n-> (((((61*n+69)*n+145)*n+195)*n+154)*n+96)*n/6!:
    seq(a(n), n=0..40);

Formula

G.f.: -(4*x^4+21*x^3+27*x^2+8*x+1)*x / (x-1)^7.
a(n) = (61*n^6+69*n^5+145*n^4+195*n^3+154*n^2+96*n)/6!.

A290362 Number of 8-leaf rooted trees with n levels.

Original entry on oeis.org

0, 1, 22, 223, 1344, 5727, 19193, 54046, 133476, 297633, 611644, 1175845, 2138500, 3711279, 6187767, 9965276, 15570232, 23687409, 35193282, 51193771, 73066648, 102508879, 141589173, 192806010, 259151420, 344180785, 452088936, 587792817, 757020988, 966410239
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Crossrefs

Row n=8 of A290353.

Programs

  • Maple
    a:= n-> ((((((272*n+273)*n+749)*n+1365)*n+1043)*n+882)*n+456)*n/7!:
    seq(a(n), n=0..40);
  • Mathematica
    LinearRecurrence[{8,-28,56,-70,56,-28,8,-1},{0,1,22,223,1344,5727,19193,54046},30] (* Harvey P. Dale, Oct 16 2017 *)

Formula

G.f.: (5*x^5+57*x^4+120*x^3+75*x^2+14*x+1)*x / (x-1)^8.
a(n) = (272*n^7+273*n^6+749*n^5+1365*n^4+1043*n^3+882*n^2+456*n)/7!.

A290363 Number of 9-leaf rooted trees with n levels.

Original entry on oeis.org

0, 1, 30, 424, 3357, 17836, 71769, 236093, 667335, 1676364, 3832477, 8113347, 16112746, 30319341, 54481246, 94072398, 156878210, 253719339, 399333792, 613438978, 921996699, 1358705458, 1966745847, 2800806163, 3929416785, 5437623230, 7430029191, 10034242245
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2017

Keywords

Crossrefs

Row n=9 of A290353.

Programs

  • Maple
    a:= n-> (((((((1385*n+1124)*n+4018)*n+6776)*n+7945)*n
            +9716)*n+6812)*n+2544)*n/8!:
    seq(a(n), n=0..40);
  • Mathematica
    CoefficientList[Series[-(8*x^6 + 135*x^5 + 493*x^4 + 537*x^3 + 190*x^2 + 21*x + 1)*x/(x - 1)^9, {x, 0, 30}], x] (* Wesley Ivan Hurt, Oct 14 2023 *)

Formula

G.f.: -(8*x^6+135*x^5+493*x^4+537*x^3+190*x^2+21*x+1)*x / (x-1)^9.
a(n) = (1385*n^8 +1124*n^7 +4018*n^6 +6776*n^5 +7945*n^4 +9716*n^3 +6812*n^2 +2544*n)/8!.
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