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.

A304319 O.g.f. A(x) satisfies: [x^n] exp( n*(n+1) * x ) / A(x) = 0 for n>0.

Original entry on oeis.org

1, 2, 10, 104, 1772, 42408, 1303504, 48736000, 2139552016, 107629121888, 6094743943584, 383305860004992, 26491391713168640, 1994924925169038848, 162537118868301414912, 14243360542620058589184, 1335710880923054761115904, 133461369304858515494530560, 14154134380237986764584033792, 1587931951984022880659170662400
Offset: 0

Views

Author

Paul D. Hanna, May 11 2018

Keywords

Comments

It is striking that the coefficients of o.g.f. A(x) consist entirely of integers.
Note that if [x^n] exp( (n+1)*(n+2)*x ) / G(x) = 0 then G(x) does not consist entirely of integer coefficients.

Examples

			O.g.f.: A(x) = 1 + 2*x + 10*x^2 + 104*x^3 + 1772*x^4 + 42408*x^5 + 1303504*x^6 + 48736000*x^7 + 2139552016*x^8 + 107629121888*x^9 + 6094743943584*x^10 + ...
ILLUSTRATION OF DEFINITION.
The table of coefficients of x^k/k! in exp(n*(n+1)*x) / A(x) begins:
n=0: [1, -2, -12, -432, -32640, -4176000, -804504960, -216834831360, ...];
n=1: [1, 0, -16, -520, -36432, -4520768, -856647680, -228458074752, ...];
n=2: [1, 4, 0, -648, -46032, -5341824, -974612736, -254049782400, ...];
n=3: [1, 10, 84, 0, -56832, -6922368, -1194341760, -299397745152, ...];
n=4: [1, 18, 308, 4448, 0, -8528000, -1573784960, -376524725760, ...];
n=5: [1, 28, 768, 20088, 444720, 0, -1938504960, -502258872960, ...];
n=6: [1, 40, 1584, 61560, 2286768, 72032832, 0, -618983309952, ...];
n=7: [1, 54, 2900, 154352, 8074368, 404450176, 17201640064, 0, ...];
n=8: [1, 70, 4884, 339120, 23357568, 1583068032, 102886277760, 5682964174848, 0, ...]; ...
in which the main diagonal is all zeros after the initial term, illustrating that [x^n] exp( n*(n+1)*x ) / A(x) = 0 for n>=0.
LOGARITHMIC DERIVATIVE.
The logarithmic derivative of A(x) yields the o.g.f. of A304317:
A'(x)/A(x) = 2 + 16*x + 260*x^2 + 6200*x^3 + 191832*x^4 + 7235152*x^5 + 320372320*x^6 + 16243028896*x^7 + 926219213216*x^8 + 58608051937536*x^9 + 4072302306624576*x^10 + ...+ A304317(n)*x^n + ...

Links

Crossrefs

Cf. A304317, A304318, A304320, A304863, A304864, A304865.

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0); m=#A; A[m] = Vec( exp(x*m*(m-1) +x*O(x^m)) / Ser(A) )[m] ); A[n+1]}
for(n=0,25, print1( a(n),", "))

Formula

a(n) ~ sqrt(1-c) * 2^(2*n) * n^(n - 1/2) / (sqrt(Pi) * c^(n + 1/2) * (2-c)^n * exp(n)), where c = -A226775 = -LambertW(-2*exp(-2)). - Vaclav Kotesovec, Aug 31 2020

A304864 O.g.f. A(x) satisfies: [x^n] exp( n*(n+3) * x ) / A(x) = 0 for n>0.

Original entry on oeis.org

1, 4, 26, 288, 5012, 122608, 3869456, 148838816, 6721823600, 347434618432, 20180665251360, 1299399587904384, 91769604540962816, 7049102617933604352, 584848346900868001792, 52109481481410100183552, 4961586770799906448318208, 502707358017324652042259456, 54000226687663791374322245120, 6129804668943947684749062516736, 733179029209444818691965317379072
Offset: 0

Views

Author

Paul D. Hanna, May 19 2018

Keywords

Examples

			O.g.f.: A(x) = 1 + 4*x + 26*x^2 + 288*x^3 + 5012*x^4 + 122608*x^5 + 3869456*x^6 + 148838816*x^7 + 6721823600*x^8 + 347434618432*x^9 + 20180665251360*x^10 + ...
ILLUSTRATION OF DEFINITION.
The table of coefficients of x^k/k! in exp(n*(n+3)*x) / A(x) begins:
n=0: [1, -4, -20, -864, -72576, -10060800, -2068882560, -589017945600, ...];
n=1: [1, 0, -36, -1232, -89088, -11667456, -2328963200, -650497926144, ...];
n=2: [1, 6, 0, -1664, -125136, -14853600, -2803074560, -757869964800, ...];
n=3: [1, 14, 160, 0, -162000, -20768352, -3651775488, -937273259520, ...];
n=4: [1, 24, 540, 10000, 0, -26468352, -5107476608, -1241737082880, ...];
n=5: [1, 36, 1260, 41536, 1133184, 0, -6460818560, -1740188582400, ...];
n=6: [1, 50, 2464, 118368, 5374512, 202760544, 0, -2192436486144, ...];
n=7: [1, 66, 4320, 279136, 17619504, 1054101600, 52553405440, 0, ...];
n=8: [1, 84, 7020, 582400, 47760000, 3832731648, 292170316672, 18603667330560, 0, ...]; ...
RELATED SERIES.
The logarithmic derivative of A(x) yields:
A'(x)/A(x) = 4 + 36*x + 616*x^2 + 15496*x^3 + 504624*x^4 + 19947072*x^5 + 921521248*x^6 + 48536700064*x^7 + 2864002270720*x^8 + 186878075521216*x^9 + ...
1 - 1/A(x) = 4*x + 10*x^2 + 144*x^3 + 3024*x^4 + 83840*x^5 + 2873448*x^6 + 116868640*x^7 + 5488631808*x^8 + 291890096640*x^9 + 17321970359200*x^10 + ...

Crossrefs

Cf. A304322, A304318, A304319, A304863, A304865.

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0); m=#A; A[m] = Vec( exp(x*(m-1)*(m+2) +x*O(x^m)) / Ser(A) )[m] ); A[n+1]}
for(n=0, 25, print1( a(n), ", "))

A304865 O.g.f. A(x) satisfies: [x^n] exp( n*(n+4) * x ) / A(x) = 0 for n>0.

Original entry on oeis.org

1, 5, 37, 434, 7751, 193101, 6200872, 242667316, 11144759839, 585318934391, 34511211188637, 2253285826341378, 161201686356627524, 12530568505972885004, 1051099249634285619168, 94603882448795669308980, 9092091650779263675187695, 929177036869575506758681035, 100608724821944458615599713935, 11504982932704269804549116593702, 1385525417578463389730054278506959
Offset: 0

Views

Author

Paul D. Hanna, May 19 2018

Keywords

Examples

			O.g.f.: A(x) = 1 + 5*x + 37*x^2 + 434*x^3 + 7751*x^4 + 193101*x^5 + 6200872*x^6 + 242667316*x^7 + 11144759839*x^8 + 585318934391*x^9 + 34511211188637*x^10 + ...
ILLUSTRATION OF DEFINITION.
The table of coefficients of x^k/k! in exp(n*(n+4)*x) / A(x) begins:
n=0: [1, -5, -24, -1134, -100608, -14542200, -3095496000, -907608905280, ...];
n=1: [1, 0, -49, -1744, -128763, -17383400, -3572628125, -1024052930280, ...];
n=2: [1, 7, 0, -2430, -189600, -22895928, -4410982656, -1218708054720, ...];
n=3: [1, 16, 207, 0, -250107, -33107544, -5910144669, -1540910769048, ...];
n=4: [1, 27, 680, 13970, 0, -42775928, -8486494016, -2090851421760, ...];
n=5: [1, 40, 1551, 56376, 1681797, 0, -10852876125, -2994692165280, ...];
n=6: [1, 55, 2976, 156546, 7748832, 316211400, 0, -3807596825280, ...];
n=7: [1, 72, 5135, 360920, 24718725, 1597879072, 85448027299, 0, ...];
n=8: [1, 91, 8232, 738450, 65376768, 5650680456, 462123838656, 31350065660352, 0, ...]; ...
RELATED SERIES.
The logarithmic derivative of A(x) yields:
A'(x)/A(x) = 5 + 49*x + 872*x^2 + 22661*x^3 + 759915*x^4 + 30843448*x^5 + 1459277062*x^6 + 78529473925*x^7 + 4724556111179*x^8 + 313739794874469*x^9 + ...
1 - 1/A(x) = 5*x + 12*x^2 + 189*x^3 + 4192*x^4 + 121185*x^5 + 4299300*x^6 + 180081132*x^7 + 8675950464*x^8 + 471853727865*x^9 + 28563862383700*x^10 + ...

Crossrefs

Cf. A304322, A304318, A304319, A304863, A304864.

Programs

  • PARI
    {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0); m=#A; A[m] = Vec( exp(x*(m-1)*(m+3) +x*O(x^m)) / Ser(A) )[m] ); A[n+1]}
for(n=0, 25, print1( a(n), ", "))
Showing 1-3 of 3 results.

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