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 1-5 of 5 results.

A260578 Coefficients in asymptotic expansion of sequence A259869.

Original entry on oeis.org

1, 0, -2, -6, -29, -196, -1665, -16796, -194905, -2549468, -37055681, -592013436, -10307671769, -194225544124, -3937581243201, -85460277981116, -1977127315636969, -48573021658496348, -1262954975286604673, -34650561545808167292, -1000438355724912080873
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 29 2015

Keywords

Comments

For k > 1 is a(k) negative.

Examples

			A259869(n) / (n!/exp(1)) ~ 1 - 2/n^2 - 6/n^3 - 29/n^4 - 196/n^5 - 1665/n^6 - ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 20; b = CoefficientList[Assuming[Element[x, Reals], Series[x^2*E^(2 + 2/x)/ExpIntegralEi[1 + 1/x]^2, {x, 0, nmax}]], x]; Flatten[{1, Table[Sum[b[[k+1]]*StirlingS2[n-1, k-1], {k, 1, n}], {n, 1, nmax}]}] (* Vaclav Kotesovec, Aug 03 2015 *)

Formula

a(k) ~ -k! / (2 * exp(1) * (log(2))^(k+1)).

A259870 a(0)=0, a(1)=1; a(n) = n*a(n-1) + (n-2)*a(n-2) - Sum_{j=1..n-1} a(j)*a(n-j).

Original entry on oeis.org

0, 1, 1, 2, 5, 17, 74, 401, 2609, 19802, 171437, 1664585, 17892938, 210771761, 2698597601, 37301188610, 553473138677, 8773014886289, 147928235322314, 2643635547262049, 49909639472912177, 992516629078846010, 20736210820909594109, 454084963076923193321
Offset: 0

Views

Author

N. J. A. Sloane, Jul 09 2015

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 25; CoefficientList[Assuming[Element[x, Reals], Series[-1/(ExpIntegralEi[1 + 1/x]/Exp[1 + 1/x] - 1) - 1, {x, 0, nmax}]], x] (* Vaclav Kotesovec, Aug 05 2015 *)
  • PARI
    a=vector(30); a[1]=0; a[2]=1; for(n=2, #a-1, a[n+1] = n*a[n] + (n-2)*a[n-1] - sum(j=1, n-1, a[j+1]*a[n-j+1])); a \\ Colin Barker, Jul 09 2015

Formula

Martin and Kearney (2015) give a g.f.
a(n) ~ (n-1)! / exp(1) * (1 + 2/n + 5/n^2 + 17/n^3 + 74/n^4 + 395/n^5 + 2526/n^6 + 19087/n^7 + 168603/n^8 + 1723065/n^9 + 20148031/n^10), for coefficients see A260948. - Vaclav Kotesovec, Jul 29 2015

A260949 Coefficients in asymptotic expansion of sequence A259871.

Original entry on oeis.org

1, 4, 16, 76, 416, 2576, 17840, 137268, 1170104, 11050940, 115885968, 1353366864, 17640817784, 256630492660, 4153220868128, 74315436120300, 1458541231513152, 31131651836906752, 716862465409883040, 17683184383300077828, 464519709712796199816
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 05 2015

Keywords

Examples

			A259871(n)/((n-1)!/exp(1)) ~ 1 + 4/n + 16/n^2 + 76/n^3 + 416/n^4 + 2576/n^5 + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 25; b = CoefficientList[Assuming[Element[x, Reals], Series[x/(2*ExpIntegralEi[1 + 1/x]/Exp[1 + 1/x] - 1)^2, {x, 0, nmax+1}]], x]; Table[Sum[b[[k+1]]*StirlingS2[n, k-1], {k, 1, n+1}], {n, 0, nmax}]

Formula

a(k) ~ 4 * exp(-1) * (k-1)! / (log(2))^k.

A260950 Coefficients in asymptotic expansion of sequence A259872.

Original entry on oeis.org

1, -2, 1, 1, -10, -61, -382, -3489, -39001, -484075, -6619449, -99610098, -1638687448, -29255834780, -563343011377, -11639759292186, -256916737692132, -6034068201092777, -150271333127027481, -3955735249215111270, -109757859467421502791
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 05 2015

Keywords

Examples

			A259872(n)/((n-1)!/exp(1)) ~ 1 - 2/n + 1/n^2 + 1/n^3 - 10/n^4 - 61/n^5 - ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 25; b = CoefficientList[Assuming[Element[x, Reals], Series[x/(ExpIntegralEi[1 + 1/x]/Exp[1 + 1/x] + 1)^2, {x, 0, nmax+1}]], x]; Table[Sum[b[[k+1]]*StirlingS2[n, k-1], {k, 1, n+1}], {n, 0, nmax}]

Formula

a(k) ~ -2 * exp(-1) * (k-1)! / (log(2))^k.

A305275 Coefficients in asymptotic expansion of sequence A302557.

Original entry on oeis.org

1, 0, 2, 6, 35, 256, 2187, 21620, 243947, 3098528, 43799819, 682540780, 11630529643, 215190967544, 4296657514283, 92083313483300, 2108244638675035, 51350077108834832, 1325682930813985547, 36157047428501464220, 1038793351537388253211, 31354977545074731373512
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 18 2018

Keywords

Examples

			A302557(n) / (exp(-1) * n!) ~ 1 + 2/n^2 + 6/n^3 + 35/n^4 + 256/n^5 + 2187/n^6 + ...
		

Crossrefs

Formula

a(k) ~ k! / (2 * exp(1) * (log(2))^(k+1)).
Showing 1-5 of 5 results.