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.

Showing 1-6 of 6 results.

A297328 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)^k.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 3, 0, 1, 3, 7, 6, 0, 1, 4, 12, 18, 14, 0, 1, 5, 18, 37, 49, 25, 0, 1, 6, 25, 64, 114, 114, 56, 0, 1, 7, 33, 100, 219, 312, 282, 97, 0, 1, 8, 42, 146, 375, 676, 855, 624, 198, 0, 1, 9, 52, 203, 594, 1276, 2030, 2178, 1422, 354, 0, 1, 10, 63, 272, 889, 2196, 4155, 5736, 5496, 3058, 672, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Examples

			G.f. of column k: A_k(x) = 1 + k*x + (1/2)*k*(k + 5)*x^2 + (1/6)*k*(k^2 + 15*k + 20)*x^3 + (1/24)*k*(k^3 + 30*k^2 + 155*k + 150)*x^4 + (1/120)*k*(k^4 + 50*k^3 + 575*k^2 + 1750*k + 624)*x^5 + ...
Square array begins:
  1,   1,    1,    1,    1,     1,  ...
  0,   1,    2,    3,    4,     5,  ...
  0,   3,    7,   12,   18,    25,  ...
  0,   6,   18,   37,   64,   100,  ...
  0,  14,   49,  114,  219,   375,  ...
  0,  25,  114,  312,  676,  1276,  ...
		

Crossrefs

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[Product[1/(1 - i x^i)^k, {i, 1, n}], {x, 0, n}]][j - n], {j, 0, 11}, {n, 0, j}] // Flatten
  • PARI
    first(n, k) = my(res = matrix(n, k)); for(u=1, k, my(col = Vec(prod(j=1, n, 1/(1 - j*x^j)^(u-1)) + O(x^n))); for(v=1, n, res[v, u] = col[v])); res \\ Iain Fox, Dec 28 2017

Formula

G.f. of column k: Product_{j>=1} 1/(1 - j*x^j)^k.
A(0,k) = 1; A(n,k) = (k/n) * Sum_{j=1..n} A078308(j) * A(n-j,k). - Seiichi Manyama, Aug 16 2023

A297322 a(n) = [x^n] Product_{k>=1} (1 + k*x^k)^n.

Original entry on oeis.org

1, 1, 5, 28, 137, 726, 3896, 21071, 115089, 633007, 3500740, 19448573, 108458924, 606787572, 3404112479, 19142919543, 107874784017, 609021410570, 3443952349385, 19503777943838, 110599636109572, 627924447630011, 3568885868192419, 20304321490356084
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Crossrefs

Main diagonal of A297321.

Programs

  • Maple
    f:= proc(n) local k;
    coeff(series(mul((1+k*x^k)^n,k=1..n),x,n+1),x,n);
    end proc:
    map(f, [$0..30]); # Robert Israel, Dec 28 2017
  • Mathematica
    Table[SeriesCoefficient[Product[(1 + k x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 24}]

Formula

a(n) = A297321(n,n).
a(n) ~ c * d^n / sqrt(n), where d = 5.814548482877687529318372516965305077397562... and c = 0.2563102401728134539247148322678842806264... - Vaclav Kotesovec, Aug 01 2019

A297324 a(n) = [x^n] Product_{k>=1} (1 - k*x^k)^n.

Original entry on oeis.org

1, -1, -3, 8, 9, -26, -168, 489, 1041, -5599, 12, 27103, 23436, -222912, -435473, 3177433, 375569, -24956018, 6931209, 181844002, 57372644, -2158209675, 853739235, 20642183588, -25063980804, -148768035501, 224915906836, 1322267927471, -2337343745721, -12604818831294
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Crossrefs

Main diagonal of A297323.

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[(1 - k x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 29}]

Formula

a(n) = A297323(n,n).

A297326 a(n) = [x^n] Product_{k>=1} 1/(1 + k*x^k)^n.

Original entry on oeis.org

1, -1, -1, -1, 27, -76, 95, -295, 2035, -8119, 22714, -66793, 254223, -988651, 3444055, -11402626, 39248691, -141740051, 511583207, -1798826901, 6256648862, -22054706773, 78889160635, -281698897727, 996551999479, -3520566280801, 12522382445455, -44731559517301
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Crossrefs

Main diagonal of A297325.

Programs

  • Maple
    f:= proc(n) local k;
    coeff(series(mul(1/(1+k*x^k)^n,k=1..n),x,n+1),x,n);
    end proc:
    map(f, [$0..30]); # Robert Israel, Dec 28 2017
  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 + k x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 27}]

Formula

a(n) = A297325(n,n).

A298985 a(n) = [x^n] Product_{k>=1} 1/(1 - n*x^k)^k.

Original entry on oeis.org

1, 1, 8, 54, 496, 5400, 73728, 1204322, 23167808, 512093178, 12781430600, 355128859129, 10863077554224, 362572265689777, 13107541496092960, 510105773344747725, 21258690342206888192, 944467894258279964254, 44555341678790400325512, 2224158766859058600584834, 117123916650423288611260400
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 31 2018

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, k) option remember;   `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(i+j-1, j)*b(n-i*j, i-1, k)*k^j, j=0..n/i)))
        end:
    a:= n-> b(n$3):
    seq(a(n), n=0..30);  # Alois P. Heinz, Sep 23 2018
  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - n x^k)^k, {k, 1, n}], {x, 0, n}], {n, 0, 20}]

Formula

a(n) ~ n^n. - Vaclav Kotesovec, Feb 02 2018

A301577 G.f. A(x) satisfies: A(x) = Product_{k>=1} 1/(1 - k*x^k*A(x)^k).

Original entry on oeis.org

1, 1, 4, 16, 75, 366, 1887, 10010, 54493, 302302, 1703599, 9723774, 56101292, 326640411, 1916800425, 11325242328, 67316128903, 402245682741, 2414978550718, 14560379165160, 88122911824659, 535188028077586, 3260549998701951, 19921639754064470, 122041156818328779
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 23 2018

Keywords

Examples

			G.f. A(x) = 1 + x + 4*x^2 + 16*x^3 + 75*x^4 + 366*x^5 + 1887*x^6 + 10010*x^7 + 54493*x^8 + 302302*x^9 + ...
G.f. A(x) satisfies: A(x) = 1/((1 - x*A(x)) * (1 - 2*x^2*A(x)^2) * (1 - 3*x^3*A(x)^3) * ...).
log(A(x)) = x + 7*x^2/2 + 37*x^3/3 + 219*x^4/4 + 1276*x^5/5 + 7687*x^6/6 + 46551*x^7/7 + 285043*x^8/8 + ... + A297329(n)*x^n/n + ...
		

Crossrefs

Showing 1-6 of 6 results.