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.

A307874 E.g.f. A(x) satisfies: d/dx A(x) = 1 + A(log(1+x)).

Original entry on oeis.org

1, 1, 0, -1, 4, -12, -3, 640, -9721, 107849, -766116, -5716810, 438016259, -13557651987, 318299775147, -5284369281919, -5483686862123, 6119663470743306, -388801742002632589, 17841761552418336070, -645131407697518621805, 14383670984970068901209, 384858376828629625293001
Offset: 1

Views

Author

Ilya Gutkovskiy, May 02 2019

Keywords

Crossrefs

Programs

  • Mathematica
    terms = 23; A[] = 0; Do[A[x] = Normal[Integrate[1 + A[Log[1 + x] + O[x]^(terms + 1)], x] + O[x]^(terms + 1)], terms]; Rest[CoefficientList[A[x], x] Range[0, terms]!]
    a[n_] := a[n] = Sum[StirlingS1[n - 1, k] a[k], {k, 1, n - 1}]; a[1] = 1; Table[a[n], {n, 1, 23}]
  • PARI
    a_vector(n) = my(v=vector(n)); v[1]=1; for(i=1, n-1, v[i+1]=sum(j=1, i, stirling(i, j, 1)*v[j])); v; \\ Seiichi Manyama, Jun 24 2022

Formula

Recurrence: a(n+1) = Sum_{k=1..n} Stirling1(n,k) * a(k).

A355203 E.g.f. A(x) satisfies A'(x) = 1 + A(1 - exp(-x)).

Original entry on oeis.org

1, 1, 0, -2, 4, 10, -150, 838, 222, -82616, 1408364, -13862308, -18747672, 5307622274, -170657860276, 3561218897884, -33756455501714, -1481233045213718, 116803294574962288, -5108843717328225572, 157037998518149186728, -1976107915155933805542
Offset: 1

Views

Author

Seiichi Manyama, Jun 24 2022

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n)); v[1]=1; for(i=1, n-1, v[i+1]=sum(j=1, i, (-1)^(i-j)*stirling(i, j, 2)*v[j])); v;

Formula

a(1) = 1; a(n+1) = Sum_{k=1..n} (-1)^(n-k) * Stirling2(n,k) * a(k).

A355205 E.g.f. A(x) satisfies A'(x) = 1 + 2 * A(-log(1-x)).

Original entry on oeis.org

1, 2, 6, 28, 184, 1596, 17508, 235592, 3799736, 72125344, 1587567768, 40027332256, 1144113365576, 36747710168568, 1316192996129064, 52219780699310176, 2281487895137577232, 109193200290592216368, 5698144666408068511472
Offset: 1

Views

Author

Seiichi Manyama, Jun 24 2022

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n)); v[1]=1; for(i=1, n-1, v[i+1]=2*sum(j=1, i, abs(stirling(i, j, 1))*v[j])); v;

Formula

a(1) = 1; a(n+1) = 2 * Sum_{k=1..n} |Stirling1(n,k)| * a(k).

A355209 E.g.f. A(x) satisfies A'(x) = 1 + A(-2 * log(1-x)).

Original entry on oeis.org

1, 2, 10, 108, 2308, 94384, 7315728, 1077605632, 304189296192, 166216599473344, 177463576125821632, 373017466526422396288, 1552199775052648327045760, 12835792253795957289436533760, 211464475635678910995043533156352
Offset: 1

Views

Author

Seiichi Manyama, Jun 24 2022

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n)); v[1]=1; for(i=1, n-1, v[i+1]=sum(j=1, i, 2^j*abs(stirling(i, j, 1))*v[j])); v;

Formula

a(1) = 1; a(n+1) = Sum_{k=1..n} 2^k * |Stirling1(n,k)| * a(k).

A143806 Eigentriangle of A130534.

Original entry on oeis.org

1, 1, 1, 2, 3, 2, 6, 11, 12, 7, 24, 50, 70, 70, 36, 120, 274, 450, 595, 540, 250, 720, 1764, 3248, 5145, 6300, 5250, 2229
Offset: 0

Views

Author

Gary W. Adamson, Sep 01 2008

Keywords

Comments

Right border = A143805 (1, 1, 2, 7, 36, 250,...) = row sums shifted one place to the left, = (1, 2, 7, 36, 250,...). Sum of n-th row terms = rightmost term of next row.
A130534 = the Stirling cycle numbers:
1;
1, 1;
2, 3, 1;
6, 11, 6, 1;
...
The triangle by rows, applies termwise products of the eigensequence terms of A130534: (1, 1, 2, 7, 36, 250,...) = A143805; to row terms of A130534. Thus row 3 = (6, 11, 12, 7) = (6, 11, 6, 1) and termwise product of the first 4 terms of A143805: (1, 1, 2, 7).

Examples

			First few rows of the triangle:
  1;
  1, 1;
  2, 3, 2;
  6, 11, 12, 7;
  24, 50, 70, 70, 36;
  120, 274, 450, 595, 540, 250;
  720, 1764, 3248, 5145, 6300, 5250, 2229;
  ...
		

Crossrefs

Formula

Triangle read by rows, A130534 * (A143805 * 0^(n-k)); 0<=k<=n.

A317275 a(1) = 1; a(n) = Sum_{k=1..n-1} |Stirling1(n-1,k)|*a(k)*a(n-k).

Original entry on oeis.org

1, 1, 2, 9, 97, 3105, 409318, 301069244, 1523141657289, 61447697339843710, 22299766257043761657829, 80922067241038150103930448880, 3230152742688615187688660954252643194, 1547248455508510864175770056662224501358437847
Offset: 1

Views

Author

Ilya Gutkovskiy, Jul 25 2018

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := a[n] = Sum[Abs[StirlingS1[n - 1, k]] a[k] a[n - k], {k, n - 1}]; a[1] = 1; Table[a[n], {n, 14}]
Showing 1-6 of 6 results.