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 1-10 of 10 results.

A260503 Coefficients in an asymptotic expansion of sequence A003319.

Original entry on oeis.org

1, -2, -1, -5, -32, -253, -2381, -25912, -319339, -4388949, -66495386, -1100521327, -19751191053, -382062458174, -7924762051957, -175478462117633, -4132047373455024, -103115456926017761, -2718766185148876961, -75529218928863243200, -2205316818199975235447
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 27 2015

Keywords

Examples

			A003319(n) / n! ~ 1 - 2/n - 1/n^2 - 5/n^3 - 32/n^4 - 253/n^5 - 2381/n^6 - ...
		

Crossrefs

Programs

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

Formula

a(k) ~ -k! / (2 * (log(2))^(k+1)).
For n>0, Sum_{k=1..n} a(k) * Stirling1(n-1, k-1) = A259472(n). - Vaclav Kotesovec, Aug 03 2015
For n>0, a(n) = Sum_{k=1..n} A259472(k) * Stirling2(n-1, k-1). - Vaclav Kotesovec, Aug 03 2015

A256168 Coefficients in asymptotic expansion of sequence A052186.

Original entry on oeis.org

1, -2, 1, -1, -9, -59, -474, -4560, -50364, -625385, -8622658, -130751886, -2163331779, -38793751015, -749691306018, -15535914341831, -343749787006758, -8089725377931547, -201801866906374263, -5319643146604299835, -147774950436327236681
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 17 2015

Keywords

Comments

For k > 2 is a(k) negative.

Examples

			A052186(n) / n! ~ 1 - 2/n + 1/n^2 - 1/n^3 - 9/n^4 - 59/n^5 - 474/n^6 - ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 30; b = CoefficientList[Assuming[Element[x, Reals], Series[E^(2/x) / (ExpIntegralEi[1/x] + E^(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-1)! / (log(2))^k.

A260491 Coefficients in asymptotic expansion of sequence A077607.

Original entry on oeis.org

1, -4, 0, -8, -76, -752, -8460, -107520, -1522124, -23717424, -402941324, -7407988448, -146479479308, -3099229422352, -69863683041868, -1671667534710720, -42318672085310540, -1130167625049525232, -31758424368739424780, -936840101208573355680
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 27 2015

Keywords

Comments

For k > 2 is a(k) negative.

Examples

			A077607(n) / (-n!) ~ 1 - 4/n - 8/n^3 - 76/n^4 - 752/n^5 - 8460/n^6 - ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 30; b = CoefficientList[Assuming[Element[x, Reals], Series[x^4*E^(2/x)/(ExpIntegralEi[1/x] - x*E^(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 * k! / (4 * (log(2))^(k+2)).

A260532 Coefficients in asymptotic expansion of sequence A051295.

Original entry on oeis.org

1, 2, 7, 31, 165, 1025, 7310, 59284, 543702, 5618267, 65200918, 846462826, 12229783811, 195394019337, 3427472046792, 65526442181293, 1355785469986828, 30166624979467869, 717769036033944699, 18174105506247664633, 487655384740384445407, 13816406622559942660420
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 28 2015

Keywords

Examples

			A051295(n)/(n-1)! ~ 1 + 2/n + 7/n^2 + 31/n^3 + 165/n^4 + 1025/n^5 + 7310/n^6 + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 30; b = CoefficientList[Assuming[Element[x, Reals], Series[E^(2/x)*x / (ExpIntegralEi[1/x] - E^(1/x))^2, {x, 0, nmax+1}]], x]; Table[Sum[b[[k+1]] * StirlingS2[n, k-1], {k, 1, n+1}], {n, 0, nmax}] (* Vaclav Kotesovec, Aug 03 2015 *)

Formula

a(k) ~ 2 * (k-1)! / (log(2))^k.
a(n) = Sum_{k=0..n} A134378(k) * Stirling2(n, k). - Vaclav Kotesovec, Aug 04 2015

A260530 Coefficients in asymptotic expansion of sequence A051296.

Original entry on oeis.org

1, 2, 7, 35, 216, 1575, 13243, 126508, 1359437, 16312915, 217277446, 3194459333, 51557948291, 908431129702, 17376289236947, 358847480175063, 7959468559605624, 188702262366570387, 4760773506835189975, 127312428854513811012, 3596091234340397964321
Offset: 0

Views

Author

Vaclav Kotesovec, Jul 28 2015

Keywords

Examples

			A051296(n) / n! ~ 1 + 2/n + 7/n^2 + 35/n^3 + 216/n^4 + 1575/n^5 + 13243/n^6 + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 30; b = CoefficientList[Assuming[Element[x, Reals], Series[E^(2/x)*x^2 / (ExpIntegralEi[1/x] - 2*x*E^(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 * (log(2))^(k+1)).

A259869 a(0) = -1; for n > 0, number of indecomposable derangements, i.e., no fixed points, and not fixing [1..j] for any 1 <= j < n.

Original entry on oeis.org

-1, 0, 1, 2, 8, 40, 244, 1736, 14084, 128176, 1292788, 14313272, 172603124, 2252192608, 31620422980, 475350915656, 7618759828388, 129697180826512, 2337145267316500, 44446207287450968, 889595868295057364, 18693361200724345024, 411475140936880082020
Offset: 0

Views

Author

N. J. A. Sloane, Jul 09 2015

Keywords

Comments

The derangement characterization would yield a(0) = 1, but -1 is the value given in Martin and Kearney's paper. - Eric M. Schmidt, Jul 10 2015

Examples

			There are 9 derangements of 1,2,3,4. All of them are indecomposable except for 2,1,4,3. Thus a(4) = 8. - _Eric M. Schmidt_, Jul 10 2015
		

Crossrefs

Programs

  • Mathematica
    Clear[a]; a[0]=-1; a[1]=0; a[n_]:=a[n]=(n-1)*a[n-1] + (n-3)*a[n-2] + Sum[a[j]*a[n-j],{j,1,n-1}]; Table[a[n],{n,0,20}] (* Vaclav Kotesovec, Jul 29 2015 *)
    nmax = 25; CoefficientList[Assuming[Element[x, Reals], Series[-x*E^(1 + 1/x)/ExpIntegralEi[1 + 1/x], {x, 0, nmax}]], x] (* Vaclav Kotesovec, Aug 05 2015 *)
  • Sage
    def a(n) : return -1 if n==0 else 0 if n==1 else (n-1)*a(n-1) + (n-3)*a(n-2) + sum(a(j)*a(n-j) for j in [1..n-1]) # Eric M. Schmidt, Jul 10 2015

Formula

Martin and Kearney (2015) give both a recurrence and a g.f.
The recurrence is a(0)=-1, a(1)=0; a(n) = (n-1)*a(n-1) + (n-3)*a(n-2) + Sum_{j=1..n-1} a(j)*a(n-j).
a(n) ~ n!/exp(1) * (1 - 2/n^2 - 6/n^3 - 29/n^4 - 196/n^5 - 1665/n^6 - 16796/n^7 - 194905/n^8 - 2549468/n^9 - 37055681/n^10), for coefficients see A260578. - Vaclav Kotesovec, Jul 28 2015
G.f.: -1 + x^2/(1 - 2*x - 4*x^2/(1 - 4*x - 9*x^2/(1 - 6*x - 16*x^2/(1 - ...)))), a continued fraction. - Ilya Gutkovskiy, Aug 22 2018

Extensions

More terms from and definition edited by Eric M. Schmidt, Jul 10 2015

A260948 Coefficients in asymptotic expansion of sequence A259870.

Original entry on oeis.org

1, 2, 5, 17, 74, 395, 2526, 19087, 168603, 1723065, 20148031, 266437102, 3938754720, 64391209604, 1152961464743, 22424127879610, 470399253269776, 10579865622308851, 253840801521314095, 6468953273455413674, 174452533187403980841, 4962228907578051232358
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 05 2015

Keywords

Examples

			A259870(n)/((n-1)!/exp(1)) ~ 1 + 2/n + 5/n^2 + 17/n^3 + 74/n^4 + 395/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.

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 1-10 of 10 results.