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 11 results. Next

A144659 a(n) = A001516(n)/2.

Original entry on oeis.org

0, 0, 3, 60, 990, 16485, 292215, 5602338, 116549370, 2627202105, 63960690420, 1675359272730, 47031228602358, 1409683851264780, 44956320071089245, 1520493296271210030, 54376042036599780570, 2050556012681642525763, 81336729496634645414265, 3385729099078381669910310
Offset: 0

Views

Author

N. J. A. Sloane, Jan 30 2009

Keywords

Formula

Also a(n) = 3*A144507(n).
Also a(n) = Sum_{k} binomial(k-n,2) T(n,k) where T(n,k) is the triangle in A144331.

A001514 Bessel polynomial {y_n}'(1).

Original entry on oeis.org

0, 1, 9, 81, 835, 9990, 137466, 2148139, 37662381, 733015845, 15693217705, 366695853876, 9289111077324, 253623142901401, 7425873460633005, 232122372003909045, 7715943399320562331, 271796943164015920914, 10114041937573463433966
Offset: 0

Views

Author

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    (As in A001497 define:) f := proc(n) option remember; if n <=1 then (1+x)^n else expand((2*n-1)*x*f(n-1)+f(n-2)); fi; end;
    [seq( subs(x=1,diff(f(n),x)),n=0..60)];
    f2:=proc(n) local k; add((n+k+2)!/((n-k)!*k!*2^k),k=0..n); end; [seq(f2(n),n=0..60)]; # uses a different offset
  • Mathematica
    Table[Sum[(n+k+1)!/((n-k-1)!*k!*2^(k+1)), {k,0,n-1}], {n,0,20}] (* Vaclav Kotesovec, Jul 22 2015 *)
    Join[{0}, Table[n*Pochhammer[1/2, n]*2^n* Hypergeometric1F1[1 - n, -2*n, 2], {n,1,50}]] (* G. C. Greubel, Aug 14 2017 *)
  • PARI
    for(n=0,50, print1(sum(k=0,n-1, (n+k+1)!/((n-k-1)!*k!*2^(k+1))), ", ")) \\ G. C. Greubel, Aug 14 2017

Formula

a(n) = (1/2) * Sum_{k=0..n} (n+k+2)!/((n-k)!*k!*2^k) (with a different offset).
D-finite with recurrence: (n-1)^2 * a(n) = (2*n-1)*(n^2 - n + 1)*a(n-1) + n^2*a(n-2). - Vaclav Kotesovec, Jul 22 2015
a(n) ~ 2^(n+1/2) * n^(n+1) / exp(n-1). - Vaclav Kotesovec, Jul 22 2015
a(n) = n*2^n*(1/2){n}*hypergeometric1f1(1-n, -2*n, 2), where (a){n} is the Pochhammer symbol. - G. C. Greubel, Aug 14 2017
From G. C. Greubel, Aug 16 2017: (Start)
G.f.: (1/(1-t))*hypergeometric2f0(2, 3/2; -; 2*t/(1-t)^2).
E.g.f.: (1 - 2*x)^(-3/2)*((1 - x)*sqrt(1 - 2*x) + (3*x - 1))*exp((1 - sqrt(1 - 2*x))). (End)

A144507 Column 4 of triangle in A144505.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 20, 330, 5495, 97405, 1867446, 38849790, 875734035, 21320230140, 558453090910, 15677076200786, 469894617088260, 14985440023696415, 506831098757070010, 18125347345533260190, 683518670893880841921, 27112243165544881804755, 1128576366359460556636770
Offset: 0

Views

Author

N. J. A. Sloane, Dec 14 2008

Keywords

Crossrefs

Programs

  • Magma
    I:=[0,0,0,0,0,1]; [n le 6 select I[n] else ((2*n-9)*(n^2-9*n+22)*Self(n-1) + (n-3)*(n-4)*Self(n-2))/((n-5)*(n-6)): n in [1..32]]; // G. C. Greubel, Oct 10 2023
    
  • Maple
    f4:=proc(n) local k; add((n+k-1)!/(4!*(n-k-5)!*k!*2^k),k=0..n-5); end;
    [seq(f4(n), n=0..60)];
  • Mathematica
    Table[Sum[1/6 (n+k+2)!/(2^(k+2) (n-k-2)! k!), {k,0,n-2}], {n, -3, 20}] (* Vincenzo Librandi, Jan 27 2020 *)
  • SageMath
    @CachedFunction
    def A144507(n): return sum(binomial(n-5,j)*rising_factorial(n-4,j+4)/(24*2^j) for j in range(n-4))
    [A144507(n) for n in range(31)] # G. C. Greubel, Oct 10 2023

Formula

a(n) = (1/4!)*Sum_{k=0..n-5} (n+k-1)!/((n-k-5)!*k!*2^k).
a(n) = A001516(n-3)/6 for n > 2. [Corrected by Georg Fischer, Jan 25 2020]
a(n) = ( (2*n-7)*(n^2 -7*n +14)*a(n-1) + (n-2)*(n-3)*a(n-2) )/((n-4)*(n-5)), with a(0)=a(1)=a(2)=a(3)=a(4)=0, and a(5)=1. - G. C. Greubel, Oct 10 2023

A065944 Bessel polynomial {y_n}''(-1).

Original entry on oeis.org

0, 0, 6, -60, 720, -9870, 153510, -2679264, 51934680, -1107917910, 25807660560, -651977992380, 17758547202396, -518856566089680, 16188283372489410, -537210169663283760, 18894951642157260480, -702160022681408982114
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • GAP
    f:=Factorial;; Concatenation([0,0], List([2..20], n-> Sum([0..n-2], k-> (-1)^k*f(n+k+2)/(2^(k+2)*f(n-k-2)*f(k)) ))); # G. C. Greubel, Jul 10 2019
  • Magma
    f:=Factorial; [0,0] cat [(&+[((-1)^k*f(n+k+2)/(2^(k+2)*f(n-k-2) *f(k))): k in [0..n-2]]): n in [2..20]]; // G. C. Greubel, Jul 10 2019
    
  • Mathematica
    Table[Sum[(n+k+2)!*(-1)^k/(2^(k+2)*(n-k-2)!*k!), {k,0,n-2}], {n,0,20}] (* Vaclav Kotesovec, Jul 22 2015 *)
    Join[{0, 0}, Table[4*n*(n-1)*Pochhammer[1/2, n]*(-2)^(n-2)* Hypergeometric1F1[2-n, -2*n, -2], {n, 2,20}]] (* G. C. Greubel, Aug 14 2017 *)
  • PARI
    for(n=0,20, print1(sum(k=0,n-2, (n+k+2)!*(-1)^k/(2^(k+2)*(n-k-2)!*k!)), ", ")) \\ G. C. Greubel, Aug 14 2017
    
  • Sage
    f=factorial; [0,0]+[sum((-1)^k*f(n+k+2)/(2^(k+2)*f(n-k-2)*f(k)) for k in (0..n-2)) for n in (2..20)] # G. C. Greubel, Jul 10 2019
    

Formula

Recurrence: (n-2)*(n-1)*a(n) = -(n-2)*(n+1)*(2*n-1)*a(n-1) + n*(n+1)*a(n-2). - Vaclav Kotesovec, Jul 22 2015
a(n) ~ (-1)^n * 2^(n+1/2) * n^(n+2) / exp(n+1). - Vaclav Kotesovec, Jul 22 2015
From G. C. Greubel, Aug 14 2017: (Start)
a(n) = 2*n*(n-1)*(1/2){n}*(-2)^(n - 1)* hypergeometric1f1(2 - n, -2*n, -2), where (a){n} is the Pochhammer symbol.
E.g.f.: (1 + 2*x)^(-5/2)*(x*(x + 2)*sqrt(1 + 2*x) + (2*x^3 - 2*x)) * exp(-1 + sqrt(1 + 2*x)). (End)
G.f.: (6*x^2/(1-x)^5)*hypergeometric2f0(3,5/2; - ; -2*x/(1-x)^2). - G. C. Greubel, Aug 16 2017

A065945 Bessel polynomial {y_n}''(2).

Original entry on oeis.org

0, 0, 6, 210, 6390, 201810, 6895140, 257335596, 10489055220, 465303486780, 22363517407770, 1159112646836430, 64499453473280826, 3837361123234687230, 243168894263042103720, 16356164256377393353080, 1164094991704907423494920
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • Mathematica
    Join[{0, 0}, Table[4*n*(n - 1)*Pochhammer[1/2, n]*4^(n - 2)* Hypergeometric1F1[2 - n, -2*n, 1], {n,2,50}]] (* G. C. Greubel, Aug 14 2017 *)
  • PARI
    for(n=0,50, print1(sum(k=0,n-2, ((n+k+2)!/(4*k!*(n-k-2)!))), ", ")) \\ G. C. Greubel, Aug 14 2017

Formula

From G. C. Greubel, Aug 14 2017: (Start)
a(n) = 4*n*(n - 1)*(1/2)_{n}*4^(n - 2)*hypergeometric1f1(2-n, -2*n, 1).
E.g.f.: (-1/16)*(1 - 4*x)^(-5/2)*((56*x^2 - 44*x + 6)*sqrt(1 - 4*x) + (16*x^3 - 180*x^2 + 56*x - 6))*exp((1 - sqrt(1 - 4*x))/2). (End)
G.f.: (6*x^2/(1-x)^5)*hypergeometric2f0(3,5/2; - ; 4*x/(1-x)^2). - G. C. Greubel, Aug 16 2017

A065946 Bessel polynomial {y_n}''(-2).

Original entry on oeis.org

0, 0, 6, -150, 3870, -110670, 3538500, -125941284, 4953759300, -213744815460, 10047637214010, -511403305348650, 28029852267603186, -1646397200571955650, 103190849406195456360, -6875135229835376875560, 485256294032090950981800
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • Mathematica
    Join[{0, 0}, Table[4*n*(n - 1)*Pochhammer[1/2, n]*(-4)^(n - 2)*
    Hypergeometric1F1[2 - n, -2*n, -1], {n,2,50}]] (* G. C. Greubel, Aug 14 2017 *)
  • PARI
    for(n=0,50, print1(sum(k=0,n-2, ((n+k+2)!/(4*k!*(n-k-2)!))*(-1)^k), ", ")) \\ G. C. Greubel, Aug 14 2017

Formula

From G. C. Greubel, Aug 14 2017: (Start)
a(n) = 4*n*(n - 1)*(1/2){n}*(-4)^(n - 2)*hypergeometric1f1(2-n, -2*n, -1), where (a){n} is the Pochhammer symbol.
E.g.f.: (1/16)*(1 + 4*x)^(-5/2)*((24*x^2 + 20*x + 2)*sqrt(1 + 4*x) + (16*x^3 - 12*x^2 - 24*x - 2))*exp((sqrt(1 + 4*x) -1)/2). (End)
G.f.: (6*x^2/(1-x)^5)*hypergeometric2f0(3,5/2; - ; -4*x/(1-x)^2). - G. C. Greubel, Aug 16 2017

A065947 Bessel polynomial {y_n}''(3).

Original entry on oeis.org

0, 0, 6, 300, 13320, 620130, 31406550, 1743174216, 105889417200, 7010411889690, 503353562247360, 39003404559533700, 3246506259033473436, 289042023964190515200, 27418894569798460848210, 2761554229456140638184840, 294364593823858690215256200
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • Mathematica
    Join[{0, 0}, Table[4*n*(n - 1)*Pochhammer[1/2, n]*6^(n - 2)* Hypergeometric1F1[2 - n, -2*n, 2/3], {n, 2, 50}]] (* G. C. Greubel, Aug 14 2017 *)
  • PARI
    for(n=0,50, print1(sum(k=0,n-2, ((n+k+2)!/(4*k!*(n-k-2)!))*(3/2)^k), ", ")) \\ G. C. Greubel, Aug 14 2017

Formula

From G. C. Greubel, Aug 14 2017: (Start)
a(n) = 4*n*(n - 1)*(1/2){n}*6^(n - 2)*hypergeometric1F1(2-n, -2*n, 2/3), where (a){n} is the Pochhammer symbol.
E.g.f.: (-1/81)*(1 - 6*x)^(-5/2)*((171*x^2 - 90*x + 8)*sqrt(1 - 6*x) + (54*x^3 - 648*x^2 + 114*x - 8))*exp((1 - sqrt(1 - 6*x))/3). (End)
G.f.: (6*x^2/(1-x)^5)*hypergeometric2F0(3,5/2; - ; 6*x/(1-x)^2). - G. C. Greubel, Aug 16 2017

A065948 Bessel polynomial {y_n}''(-3).

Original entry on oeis.org

0, 0, 6, -240, 9540, -415590, 20134590, -1082674404, 64221641820, -4173853100670, 295282282905720, -22605059036265420, 1862664627479732076, -164425432052147568120, 15483794266369962976170, -1549617160894627918342620, 164264715996348003982855020
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • Mathematica
    Join[{0, 0}, Table[4*n*(n - 1)*Pochhammer[1/2, n]*(-6)^(n - 2)* Hypergeometric1F1[2 - n, -2*n, -2/3], {n, 2, 50}]] (* G. C. Greubel, Aug 15 2017 *)
  • PARI
    for(n=0,50, print1(sum(k=0,n-2, ((n+k+2)!/(4*k!*(n-k-2)!))*(-3/2)^k ), ", ")) \\ G. C. Greubel, Aug 15 2017

Formula

From G. C. Greubel, Aug 15 2017: (Start)
a(n) = 4*n*(n - 1)*(1/2){n}*(-6)^(n - 2)* hypergeometric1f1(2 - n; -2*n; -2/3), where (a){n} is the Pochhammer symbol.
E.g.f.: (-1/81)*(1 + 6*x)^(-5/2)*((-99*x^2 - 54*x - 4)*sqrt(1 + 6*x) + (-54*x^3 + 66*x + 4))*exp(-(1 - sqrt(1 + 6*x))/3). (End)
G.f.: (6*x^2/(1-x)^5)*hypergeometric2f0(3,5/2; - ; -6*x/(1-x)^2). - G. C. Greubel, Aug 16 2017

A065949 Bessel polynomial {y_n}'''(0).

Original entry on oeis.org

0, 0, 0, 90, 630, 2520, 7560, 18900, 41580, 83160, 154440, 270270, 450450, 720720, 1113840, 1670760, 2441880, 3488400, 4883760, 6715170, 9085230, 12113640, 15939000, 20720700, 26640900, 33906600, 42751800, 53439750, 66265290, 81557280, 99681120, 121041360, 146084400
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • Mathematica
    Drop[90*Binomial[Range[40]-3,6],5] (* Harvey P. Dale, Sep 20 2013 *)
  • PARI
    for(n=0,50, print1(90*binomial(n+3,6), ", ")) \\ G. C. Greubel, Aug 15 2017

Formula

a(n) = 90 * C(n-3, 6) = 90 * A000579(n-3). - Ralf Stephan, Sep 03 2003
From Colin Barker, Aug 01 2013: (Start)
a(n) = ((-2+n)*(-1+n)*n*(1+n)*(2+n)*(3+n))/8.
G.f.: -90*x^3 / (x-1)^7. (End)
E.g.f.: (1/8)*x^3*(120 + 90*x + 18*x^2 + x^3)*exp(x). - G. C. Greubel, Aug 15 2017

Extensions

More terms from Colin Barker, Aug 01 2013

A065950 Bessel polynomial {y_n}'''(1).

Original entry on oeis.org

0, 0, 0, 90, 3150, 81900, 1992060, 48771450, 1237774230, 32978969100, 927339227100, 27566149731120, 866148362679600, 28735959507074820, 1005105838958594100, 36999204981675832350, 1430792213377354462530, 58019598569681129648700
Offset: 0

Views

Author

N. J. A. Sloane, Dec 08 2001

Keywords

References

  • J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77.

Crossrefs

Programs

  • Magma
    [0,0,0] cat [(&+[Binomial(n-3,k)*Factorial(n+k+3)/(2^(k+3) * Factorial(n-3)): k in [0..n-3]]): n in [3..30]]; // G. C. Greubel, Sep 23 2023
    
  • Mathematica
    Join[{0,0,0}, Table[6*Binomial[n,3]*Pochhammer[1/2,n]*2^n* Hypergeometric1F1[3-n,-2*n,2], {n,3,50}]] (* G. C. Greubel, Aug 15 2017 *)
    CoefficientList[Series[(90*t^3/(1-t)^7)*HypergeometricPFQ[{4, 7/2}, {}, 2*t/(1-t)^2], {t,0,50}], t] (* G. C. Greubel, Aug 16 2017 *)
  • PARI
    for(n=0,50, print1(sum(k=0,n-3, ((n+k+3)!/(2^(k+3)*k!*(n-k-3)!))), ", ")) \\ G. C. Greubel, Aug 15 2017
    
  • SageMath
    def A065950(n): return sum(binomial(n-3,k)*rising_factorial(n-2,k+6)//2^(k+3) for k in range(n-2))
    [A065950(n) for n in range(31)] # G. C. Greubel, Sep 23 2023

Formula

a(n) = 6*binomial(n, 3)*(1/2){n}*2^n*hypergeometric1f1(3-n, -2*n, 2), where (a){n} is the Pochhammer symbol. - G. C. Greubel, Aug 15 2017
G.f.: (90*x^3/(1-x)^7)*hypergeometric2f0(4,7/2; - ; 2*x/(1-x)^2). - G. C. Greubel, Aug 16 2017
a(n) ~ 2^(n + 1/2) * n^(n+3) / exp(n-1). - Vaclav Kotesovec, Jun 09 2019
Showing 1-10 of 11 results. Next