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 1-3 of 3 results.

A308060 G.f. A(x) satisfies: A(x) = x * exp(Sum_{i>=1} Sum_{j>=1} (-1)^(j+1)*A(x^(i*j))/j).

Original entry on oeis.org

1, 1, 2, 5, 11, 26, 65, 161, 412, 1074, 2841, 7599, 20582, 56202, 154760, 429052, 1196802, 3356107, 9456737, 26760173, 76017365, 216693521, 619663800, 1777141141, 5110235884, 14730604451, 42557910762, 123210505445, 357403386959, 1038616488923, 3023329186466, 8814593734152
Offset: 1

Views

Author

Ilya Gutkovskiy, May 11 2019

Keywords

Crossrefs

Programs

  • Mathematica
    terms = 32; A[] = 0; Do[A[x] = x Exp[Sum[Sum[(-1)^(j + 1) A[x^(i j)]/j, {j, 1, terms}], {i, 1, terms}]] + O[x]^(terms + 1) // Normal, terms + 1]; Rest[CoefficientList[A[x], x]]
    a[n_] := a[n] = SeriesCoefficient[x Product[Product[(1 + x^(i j))^a[j], {j, 1, n - 1}], {i, 1, n - 1}], {x, 0, n}]; Table[a[n], {n, 1, 32}]

Formula

G.f.: x * Product_{i>=1, j>=1} (1 + x^(i*j))^a(j).
a(n) ~ c * d^n / n^(3/2), where d = 3.05850813076802274498884492525... and c = 0.46090575889706771724968759... - Vaclav Kotesovec, Nov 05 2021

A308153 G.f.: x * Product_{j>=1, k>=1} 1/(1 - a(j)*x^(j*k)).

Original entry on oeis.org

1, 1, 3, 7, 19, 47, 134, 357, 1031, 2912, 8612, 25007, 75378, 223884, 683915, 2067578, 6376800, 19503546, 60749341, 187592661, 587938043, 1831377952, 5773159368, 18092820941, 57328904204, 180657986051, 574735018826, 1820143698295, 5810522774503, 18473074695503
Offset: 1

Views

Author

Ilya Gutkovskiy, May 14 2019

Keywords

Crossrefs

Programs

  • Maple
    A:= proc(n) option remember; series(x*`if`(n=1, 1, mul(mul(
          1/(1-a(j)*x^(j*k)), k=1..(n-1)/j), j=1..n-1)), x, n+1)
        end:
    a:= n-> coeff(A(n), x, n):
    seq(a(n), n=1..35);  # Alois P. Heinz, May 14 2019
  • Mathematica
    a[n_] := a[n] = SeriesCoefficient[x Product[Product[1/(1 - a[j] x^(j k)), {k, 1, n - 1}], {j, 1, n - 1}], {x, 0, n}]; Table[a[n], {n, 1, 30}]

A308152 G.f.: x * Product_{j>=1, k>=1} ((1 + x^(j*k))/(1 - x^(j*k)))^a(j).

Original entry on oeis.org

1, 2, 8, 32, 138, 612, 2864, 13712, 67416, 337482, 1716208, 8837392, 45997032, 241571408, 1278625480, 6813568656, 36524390042, 196820310100, 1065583770168, 5793299764208, 31615962617272, 173131117881312, 951040865156928, 5239171609158304, 28937688613453048
Offset: 1

Views

Author

Ilya Gutkovskiy, May 14 2019

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := a[n] = SeriesCoefficient[x Product[Product[((1 + x^(j k))/(1 - x^(j k)))^a[j], {k, 1, n - 1}], {j, 1, n - 1}], {x, 0, n}]; Table[a[n], {n, 1, 25}]
    terms = 25; A[] = 0; Do[A[x] = x Exp[2 Sum[Sum[A[x^(i (2 j - 1))]/(2 j - 1), {j, 1, terms}], {i, 1,terms}]] + O[x]^(terms + 1) // Normal, terms + 1]; Rest[CoefficientList[A[x], x]]

Formula

G.f. A(x) satisfies: A(x) = x * exp(2 * Sum_{i>=1} Sum_{j>=1} A(x^(i*(2*j-1)))/(2*j - 1)).
Showing 1-3 of 3 results.