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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A265838 Expansion of Product_{k>=1} 1/(1 - k^4*x^k).

Original entry on oeis.org

1, 1, 17, 98, 610, 2531, 18580, 72453, 449494, 2114440, 10753594, 48572844, 272867295, 1137441506, 5834448870, 27276382027, 129389072144, 576677550870, 2884567552542, 12401875640710, 59474089385344, 270438887909580, 1230979340265033, 5477371267093144
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 16 2015

Keywords

Crossrefs

Column k=4 of A292193.

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1/(1 - k^4*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ c * 3^(4*n/3), where
c = 27.2472595510480930563087281042486261391960582835336715327... if n mod 3 = 0
c = 26.8841208067599453033952496040472485838861626762931432887... if n mod 3 = 1
c = 26.9277867007233095885556073185206409643421012262073908850... if n mod 3 = 2.
G.f.: exp(Sum_{k>=1} Sum_{j>=1} j^(4*k)*x^(j*k)/k). - Ilya Gutkovskiy, Jun 14 2018

A265839 Expansion of Product_{k>=1} 1/(1 - k^5*x^k).

Original entry on oeis.org

1, 1, 33, 276, 2324, 13225, 145586, 760057, 6836328, 45996924, 322816122, 2064921330, 16881567137, 96217644312, 708147553326, 4769313137735, 31412238427954, 198869428043476, 1442034056253438, 8596120396405880, 58954590481229064, 387170921610808720
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 16 2015

Keywords

Crossrefs

Column k=5 of A292193.

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1/(1 - k^5*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ c * 3^(5*n/3), where
c = 12.8519823810391431573687005461910113782018563173082562291... if n mod 3 = 0
c = 12.4535903496941652158697054030067622653283880393322526099... if n mod 3 = 1
c = 12.5138855694494734654940524026530463555984202132997900068... if n mod 3 = 2.
G.f.: exp(Sum_{k>=1} Sum_{j>=1} j^(5*k)*x^(j*k)/k). - Ilya Gutkovskiy, Jun 14 2018

A285245 Expansion of Product_{k>=1} 1/(1 - k*x^(k^2)).

Original entry on oeis.org

1, 1, 1, 1, 3, 3, 3, 3, 7, 10, 10, 10, 18, 24, 24, 24, 44, 56, 65, 65, 105, 129, 147, 147, 227, 292, 328, 355, 515, 645, 717, 771, 1107, 1367, 1562, 1670, 2429, 2949, 3339, 3555, 5073, 6181, 6961, 7546, 10582, 13059, 14619, 15789, 21925, 26886, 30235, 32575
Offset: 0

Views

Author

Vaclav Kotesovec, Apr 15 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 100; CoefficientList[Series[Product[1/(1 - k*x^(k^2)), {k,1,nmax}], {x,0,nmax}], x]

Formula

a(n) ~ c * 2^(n/4), where
c = 6.362854320457366874306510139107365081972383711876544726... if mod(n,4)=0
c = 6.470997903106304472752360748461108347899808941622559468... if mod(n,4)=1
c = 6.154059402265470959096395812318265046714869376472639022... if mod(n,4)=2
c = 5.624747659153211728892605407048217108787120474872434485... if mod(n,4)=3

A294609 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of Product_{j>=1} 1/(1-j*x^j)^(j^(k*j)) in powers of x.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 9, 6, 1, 1, 33, 90, 14, 1, 1, 129, 2220, 1154, 25, 1, 1, 513, 59178, 264908, 17427, 56, 1, 1, 2049, 1594836, 67176362, 49163017, 309117, 97, 1, 1, 8193, 43048770, 17181595604, 152662625259, 13120646934, 6285102, 198
Offset: 0

Views

Author

Seiichi Manyama, Nov 04 2017

Keywords

Examples

			Square array begins:
    1,    1,      1,        1,           1, ...
    1,    1,      1,        1,           1, ...
    3,    9,     33,      129,         513, ...
    6,   90,   2220,    59178,     1594836, ...
   14, 1154, 264908, 67176362, 17181595604, ...
		

Crossrefs

Columns k=0..2 give A006906, A294610, A294611.
Rows n=0-1 give A000012.
Cf. A294605.

Formula

A(0,k) = 1 and A(n,k) = (1/n) * Sum_{j=1..n} (Sum_{d|j} d^(k*d+1+j/d)) * A(n-j,k) for n > 0.

A306884 Sum over all partitions of n of the power tower evaluation x^y^...^z, where x, y, ..., z are the parts in (weakly) decreasing order.

Original entry on oeis.org

1, 1, 3, 6, 14, 28, 93, 270, 86170, 7625640881546
Offset: 0

Views

Author

Alois P. Heinz, Mar 15 2019

Keywords

Comments

a(10) = 200352993...611306920 has 19729 decimal digits.

Examples

			a(0) = 1 because the empty partition () has no parts, the exponentiation operator ^ is right-associative, and 1 is the right identity of exponentiation.
a(6) = 1^1^1^1^1^1 + 2^1^1^1^1 + 2^2^1^1 + 2^2^2 + 3^1^1^1 + 3^2^1 + 3^3 + 4^1^1 + 4^2 + 5^1 + 6 = 1 + 2 + 4 + 16 + 3 + 9 + 27 + 4 + 16 + 5 + 6 = 93.
		

Crossrefs

Programs

  • Maple
    f:= l-> `if`(l=[], 1, l[1]^f(subsop(1=(), l))):
    a:= n-> add(f(sort(l, `>`)), l=combinat[partition](n)):
    seq(a(n), n=0..9);

A306895 Sum over all partitions of n of the power tower evaluation x^y^...^z, where x, y, ..., z are the parts in (weakly) increasing order.

Original entry on oeis.org

1, 1, 3, 5, 11, 18, 72, 387, 134349386, 115792089237316195423570985008687907853269984665640566457309223244801371506483
Offset: 0

Views

Author

Alois P. Heinz, Mar 15 2019

Keywords

Comments

a(10) has 40403562 decimal digits.

Examples

			a(0) = 1 because the empty partition () has no parts, the exponentiation operator ^ is right-associative, and 1 is the right identity of exponentiation.
a(6) = 1^1^1^1^1^1 + 1^1^1^1^2 + 1^1^2^2 + 2^2^2 + 1^1^1^3 + 1^2^3 + 3^3 + 1^1^4 + 2^4 + 1^5 + 6 = 1 + 1 + 1 + 16 + 1 + 1 + 27 + 1 + 16 + 1 + 6 = 72.
		

Crossrefs

Programs

  • Maple
    f:= l-> `if`(l=[], 1, l[1]^f(subsop(1=(), l))):
    a:= n-> add(f(sort(l, `<`)), l=combinat[partition](n)):
    seq(a(n), n=0..9);

A318127 Expansion of (1/(1 - x)) * Product_{k>=1} 1/(1 - k*x^k/(1 - x)^k).

Original entry on oeis.org

1, 2, 6, 19, 61, 191, 588, 1785, 5351, 15868, 46628, 135921, 393318, 1130538, 3229753, 9175347, 25931605, 72936434, 204223348, 569427145, 1581458917, 4375905243, 12065914843, 33160240020, 90848002909, 248154744196, 675932128695, 1836182233332, 4975249827916, 13447775233746
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 18 2018

Keywords

Comments

Binomial transform of A006906.

Crossrefs

Programs

  • Maple
    a:=series(1/(1-x)*mul(1/(1-k*x^k/(1-x)^k),k=1..100),x=0,30): seq(coeff(a,x,n),n=0..29); # Paolo P. Lava, Apr 02 2019
  • Mathematica
    nmax = 29; CoefficientList[Series[1/(1 - x) Product[1/(1 - k x^k/(1 - x)^k), {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 29; CoefficientList[Series[1/(1 - x) Exp[Sum[Sum[j^k x^(k j)/(k (1 - x)^(k j)), {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x]
    Table[Sum[Binomial[n, k] Total[Times @@@ IntegerPartitions[k]], {k, 0, n}], {n, 0, 29}]

Formula

G.f.: (1/(1 - x))*exp(Sum_{k>=1} Sum_{j>=1} j^k*x^(k*j)/(k*(1 - x)^(k*j))).
a(n) = Sum_{k=0..n} binomial(n,k)*A006906(k).
a(n) ~ c * (1 + 3^(1/3))^n, where c = 97923.037496367052161042295948902147352859984491653037730624387144966464... = 1/((3^(1/3) - 1) * (3^(2/3) - 2)) * Product_{k>=4} 1/(1 - k/3^(k/3)). - Vaclav Kotesovec, Aug 19 2018

A265974 Expansion of Product_{k>=1} 1/(1 - 3*k*x^k).

Original entry on oeis.org

1, 3, 15, 54, 210, 699, 2484, 7995, 26610, 84186, 269940, 839238, 2634579, 8098194, 25032282, 76388265, 233791104, 709501596, 2157488730, 6523204836, 19747491810, 59558682132, 179762506329, 541222906812, 1630300772106, 4902697929306, 14748249476553
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 19 2015

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1,
          3^n, b(n, i-1) +i*3*b(n-i, min(n-i, i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..32);  # Alois P. Heinz, Aug 23 2019
  • Mathematica
    nmax=40; CoefficientList[Series[Product[1/(1-3*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ c * 3^n, where c = Product_{m>=2} 1/(1 - m/3^(m-1)) = 5.86277744540963226378877460838259757442241952947887939654316926419876...

A265975 Expansion of Product_{k>=1} 1/(1 - 4*k*x^k).

Original entry on oeis.org

1, 4, 24, 108, 512, 2164, 9464, 39004, 163008, 663588, 2713752, 10954764, 44328512, 178160724, 716821752, 2874497660, 11532111232, 46187508676, 185028540696, 740595436652, 2964628293504, 11862432443764, 47467812675320, 189902835709212, 759756868215872
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 19 2015

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1,
          4^n, b(n, i-1) +i*4*b(n-i, min(n-i, i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..32);  # Alois P. Heinz, Aug 23 2019
  • Mathematica
    nmax=40; CoefficientList[Series[Product[1/(1-4*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ c * 4^n, where c = Product_{m>=2} 1/(1 - m/4^(m-1)) = 2.700170514502619666262858845683166558216386190684736249639219328278569...

A265976 Expansion of Product_{k>=1} 1/(1 - 5*k*x^k).

Original entry on oeis.org

1, 5, 35, 190, 1070, 5525, 29080, 147485, 752790, 3789170, 19105800, 95794930, 480650335, 2406018490, 12047084370, 60264282575, 301493182380, 1507758356660, 7540528037090, 37705593514220, 188545393000350, 942756783659980, 4713958620697385, 23570092258449540
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 19 2015

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1,
          5^n, b(n, i-1) +i*5*b(n-i, min(n-i, i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..32);  # Alois P. Heinz, Aug 23 2019
  • Mathematica
    nmax=40; CoefficientList[Series[Product[1/(1-5*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ c * 5^n, where c = Product_{m>=2} 1/(1 - m/5^(m-1)) = 1.977268427518901757865749340705853730491796767544158844539130847296...
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