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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A318263 Expansion of Product_{k>=1} (1 + Lucas(k)*x^k).

Original entry on oeis.org

1, 1, 3, 7, 11, 30, 62, 129, 235, 541, 1034, 2101, 4140, 8129, 15984, 31903, 60398, 117646, 228808, 433768, 836552, 1601282, 3031299, 5736396, 10899112, 20466182, 38556342, 72522116, 135662847, 253047629, 473785878, 878655661, 1634304062, 3033385668, 5608183925
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 22 2018

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1+LucasL[k]*x^k, {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 40; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = 1; Do[Do[poly[[j + 1]] += LucasL[k]*poly[[j - k + 1]], {j, nmax, k, -1}];, {k, 2, nmax}]; poly

Formula

From Vaclav Kotesovec, Aug 24 2018: (Start)
a(n) ~ c * A000032(n) * A000009(n) ~ c * phi^n * exp(Pi*sqrt(n/3)) / (4 * 3^(1/4) * n^(3/4)), where c = Product_{k>=1} ((1 + Lucas(k)/phi^k)/2) = 0.8503149035690839100210269103058319341315494385103929947491... and phi = A001622 = (1+sqrt(5))/2 is the golden ratio.
Equivalently, c = Product_{k>=1} (1 + (-1)^k/(2*phi^(2*k))),
c = 2/3 * QPochhammer[-1/2, -1/GoldenRatio^2]. (End)

A325537 Irregular triangle whose rows are the sorted combined parts of all strict integer partitions of n.

Original entry on oeis.org

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

Views

Author

Gus Wiseman, May 08 2019

Keywords

Examples

			The strict integer partitions of 6 are {(6), (5,1), (4,2), (3,2,1)} with multiset union {1,1,2,2,3,4,5,6}, which is row n = 6.
Triangle begins:
  1
  2
  1 2 3
  1 3 4
  1 2 3 4 5
  1 1 2 2 3 4 5 6
  1 1 2 2 3 4 4 5 6 7
  1 1 1 2 2 3 3 4 5 5 6 7 8
  1 1 1 2 2 2 3 3 3 4 4 5 5 6 6 7 8 9
		

Crossrefs

Row lengths are A015723.
Row sums are A066189.
Row products are A325504.
Run-lengths of row n are row n of A325513.

Programs

  • Mathematica
    Table[Sort[Join@@Select[IntegerPartitions[n],UnsameQ@@#&]],{n,10}]

A326884 E.g.f.: Product_{k>=1} (1 + k*(exp(x)-1)^k).

Original entry on oeis.org

1, 1, 5, 43, 377, 4291, 58745, 914803, 15641897, 298104451, 6337624985, 147137420563, 3674045105417, 98093008751011, 2793940490888825, 84812168406518323, 2737609202984488937, 93486719521251467971, 3358396276982001106265, 126434158646122122080083
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 31 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[(1+k*(Exp[x]-1)^k), {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!

Formula

a(n) = Sum_{k=0..n} A022629(k)*Stirling2(n,k)*k!.

A022630 Expansion of Product_{m>=1} (1 + m*q^m)^2.

Original entry on oeis.org

1, 2, 5, 14, 28, 64, 133, 266, 513, 1000, 1873, 3420, 6257, 11078, 19585, 34192, 58714, 99870, 168858, 281666, 467082, 768994, 1253038, 2030658, 3269551, 5227868, 8304467, 13133256, 20630535, 32250274, 50181624, 77653530, 119634925, 183532470, 280245365
Offset: 0

Views

Author

Keywords

Crossrefs

Column k=2 of A297321.

Programs

  • Magma
    Coefficients(&*[(1+m*x^m)^2:m in [1..40]])[1..40] where x is PolynomialRing(Integers()).1; // G. C. Greubel, Feb 16 2018
  • Mathematica
    nn=34; CoefficientList [Series[ Product[(1 + m*q^m)^2, {m, nn}], {q, 0, nn}],q] (* Robert G. Wilson v, Feb 08 2018 *)
  • PARI
    m=50; q='q+O('q^m); Vec(prod(n=1,m,(1+n*q^n)^2)) \\ G. C. Greubel, Feb 16 2018
    

Formula

Self-convolution of A022629. - Alois P. Heinz, Dec 28 2017
G.f.: exp(2*Sum_{j>=1} Sum_{k>=1} (-1)^(j+1)*k^j*x^(j*k)/j). - Ilya Gutkovskiy, Feb 08 2018

A092485 Expansion of Product_{m>=1} (1+m*(m+1)*q^m).

Original entry on oeis.org

1, 2, 6, 24, 44, 142, 366, 800, 1636, 4338, 10154, 18968, 42368, 80726, 183914, 401096, 729944, 1402098, 2829814, 5172416, 10600836, 21582558, 37732782, 70148512, 127184636, 236798322, 416265730, 804045376, 1514022088, 2581172630, 4596614522, 8035151408
Offset: 0

Views

Author

Jon Perry, Apr 04 2004

Keywords

Comments

Sum of product of i(i+1)-transform of terms in all partitions of n into distinct parts.

Examples

			The partitions of 6 into distinct parts are 6, 1+5, 2+4, 1+2+3, the corresponding i(i+1)-transforms are of products 6*7, 2*5*6, 2*3*4*5, 2*2*3*3*4, so 42, 60, 120, 144 and their sum is a(6) = 366.
		

Crossrefs

Programs

  • Mathematica
    Take[ CoefficientList[ Expand[ Product[1 + m(m + 1)q^m, {m, 1000}]], q], 30] (* Robert G. Wilson v, Apr 05 2004 *)

Extensions

More terms from Robert G. Wilson v, Apr 05 2004

A268501 Expansion of Product_{k>=1} ((1 + k*x^k) / (1 + x^k))^k.

Original entry on oeis.org

1, 0, 2, 6, 11, 32, 60, 148, 279, 690, 1312, 2778, 5684, 11282, 22920, 44724, 87919, 168978, 329800, 623086, 1189794, 2235744, 4189442, 7795642, 14438670, 26577246, 48616050, 88724110, 160629612, 290267100, 521225220, 933031364, 1661954928, 2950946220
Offset: 0

Views

Author

Vaclav Kotesovec, Feb 06 2016

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[((1+k*x^k)/(1+x^k))^k, {k, 1, nmax}], {x, 0, nmax}], x]

A268502 Expansion of Product_{k>=1} ((1 + k*x^k) / (1 - x^k))^k.

Original entry on oeis.org

1, 2, 8, 26, 73, 210, 558, 1460, 3663, 9090, 21846, 51690, 120140, 274480, 618656, 1374792, 3017867, 6546610, 14053312, 29852658, 62825894, 131025056, 270948160, 555811298, 1131498850, 2286780266, 4589706604, 9151298134, 18131193484, 35706460678, 69910352496
Offset: 0

Views

Author

Vaclav Kotesovec, Feb 06 2016

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[((1+k*x^k)/(1-x^k))^k, {k, 1, nmax}], {x, 0, nmax}], x]

A269154 Expansion of Product_{k>=1} (1 + k*x^k)/(1 + 2*x^k).

Original entry on oeis.org

1, -1, 2, -3, 9, -13, 31, -53, 118, -210, 452, -866, 1793, -3493, 7119, -13992, 28257, -56253, 113035, -225318, 451745, -901870, 1805976, -3609701, 7222075, -14439594, 28887060, -57763494, 115540784, -231066845, 462154358, -924282660, 1848598423, -3697142099
Offset: 0

Views

Author

Vaclav Kotesovec, Feb 20 2016

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[(1+k*x^k)/(1+2*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ c * (-2)^n, where c = Product_{k>=1} ((-2)^k + k)/((-2)^k - 1) = 0.4304067090888734207149852218007129877370867778815471457548443780472...

A301578 G.f. A(x) satisfies: A(x) = Product_{k>=1} (1 + k*x^k*A(x)^k).

Original entry on oeis.org

1, 1, 3, 12, 48, 211, 970, 4594, 22311, 110473, 555561, 2829918, 14570666, 75708835, 396481070, 2090558864, 11089276706, 59135014252, 316836936662, 1704764660218, 9207671377450, 49904141524184, 271325301723223, 1479427708380368, 8088057338101442, 44325245804200151
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 23 2018

Keywords

Examples

			G.f. A(x) = 1 + x + 3*x^2 + 12*x^3 + 48*x^4 + 211*x^5 + 970*x^6 + 4594*x^7 + 22311*x^8 + 110473*x^9 + ...
G.f. A(x) satisfies: A(x) = (1 + x*A(x)) * (1 + 2*x^2*A(x)^2) * (1 + 3*x^3*A(x)^3) * (1 + 4*x^4*A(x)^4) * ...
log(A(x)) = x + 5*x^2/2 + 28*x^3/3 + 137*x^4/4 + 726*x^5/5 + 3896*x^6/6 + 21071*x^7/7 + 115089*x^8/8 + ... + A297322(n)*x^n/n + ...
		

Crossrefs

A306918 Sum over all partitions of n into distinct parts of the power tower evaluation x^y^...^z, where x, y, ..., z are the parts in decreasing order.

Original entry on oeis.org

1, 1, 2, 5, 7, 18, 36, 118, 265, 263212, 2217881, 152599933940, 542101086242752217003726400434973829461152534, 63340828764059520458379290673240751904836319648345
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2019

Keywords

Comments

a(14) = 620606987...270037949 has 183231 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) = 3^2^1 + 4^2 + 5^1 + 6 = 9 + 16 + 5 + 6 = 36.
		

Crossrefs

Programs

  • Maple
    d:= proc(l) local i; for i to nops(l)-1 do
           if l[i]=l[i+1] then return fi od; l
        end:
    f:= l-> `if`(l=[], 1, l[1]^f(subsop(1=(), l))):
    a:= n-> add(f(l), l=map(l->d(sort(l, `>`)), combinat[partition](n))):
    seq(a(n), n=0..13);
  • Mathematica
    d[l_] := Module[{i}, For[i = 1, i <= Length[l] - 1, i++, If[l[[i]] == l[[i + 1]], Return[]]]; l];
    f[l_] := If[l == {}, 1, l[[1]]^f[Delete[l, 1]]];
    a[n_] := Sum[f[l], {l, ReverseSort /@ Select[IntegerPartitions[n], Length@# == Length@ Union@# &]}];
    a /@ Range[0, 13] (* Jean-François Alcover, May 04 2020, after Maple *)
Previous Showing 51-60 of 75 results. Next