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.

Previous Showing 11-20 of 22 results. Next

A107397 a(n) = binomial(n+6, 6) * binomial(n+8, 6).

Original entry on oeis.org

28, 588, 5880, 38808, 194040, 792792, 2774772, 8588580, 24048024, 61941880, 148660512, 335785632, 719540640, 1472290848, 2891999880, 5477788008, 10042611348, 17877713700, 30988037080, 52423371000, 86736850200, 140610670200, 223698793500, 349748200620, 538074154800
Offset: 0

Views

Author

Zerinvary Lajos, May 25 2005

Keywords

Examples

			If n=0 then C(0+6,6)*C(0+8,6) = C(6,6)*C(8,6) = 1*28 = 28.
If n=6 then C(6+6,6)*C(6+8,6) = C(12,6)*C(14,6) = 924*3003 = 2774772.
		

Crossrefs

Programs

  • Magma
    A107397:= func< n | Binomial(n+6,6)*Binomial(n+8,6) >;
    [A107397(n): n in [0..30]]; // G. C. Greubel, Feb 09 2025
    
  • Mathematica
    a[n_] := Binomial[n + 6, 6] * Binomial[n + 8, 6]; Array[a, 25, 0] (* Amiram Eldar, Sep 01 2022 *)
  • PARI
    a(n)={binomial(n+6, 6) * binomial(n+8, 6)} \\ Andrew Howroyd, Nov 08 2019
    
  • SageMath
    def A107397(n): return binomial(n+6,6)*binomial(n+8,6)
    print([A107397(n) for n in range(31)]) # G. C. Greubel, Feb 09 2025

Formula

From Amiram Eldar, Sep 01 2022: (Start)
Sum_{n>=0} 1/a(n) = 720*Pi^2 - 1740989/245.
Sum_{n>=0} (-1)^n/a(n) = 6144*log(2)/7 - 149046/245. (End)
G.f.: 28*(1 + 8*x + 15*x^2 + 8*x^3 + x^4)/(1-x)^13. - G. C. Greubel, Feb 09 2025

Extensions

a(3) corrected and terms a(11) and beyond from Andrew Howroyd, Nov 08 2019

A013648 Numbers k such that the periodic part of the continued fraction for sqrt(k) contains a single 1.

Original entry on oeis.org

3, 8, 15, 24, 35, 48, 63, 80, 99, 120, 143, 168, 175, 176, 195, 208, 224, 255, 288, 323, 360, 399, 440, 483, 528, 551, 575, 624, 675, 728, 783, 799, 840, 899, 960, 1023, 1035, 1088, 1155, 1224, 1247, 1295, 1368, 1403, 1443, 1520, 1599, 1680, 1763, 1848, 1872
Offset: 1

Views

Author

Keywords

Comments

All the terms of A005563 are here, as well as some additional terms (with even period > 2 and the digit 1 in central position) (e.g., sqrt(175) = [13,'4, 2, 1, 2, 4, 26']).

References

  • Kenneth H. Rosen, Elementary Number Theory and Its Applications, Addison-Wesley, 1984, page 426 (but beware of errors!).

Crossrefs

Programs

  • Mathematica
    Select[ Range@ 1900, !IntegerQ[ Sqrt@ #] && Count[ ContinuedFraction[ Sqrt@ #][[2]], 1] == 1 &] (* Robert G. Wilson v, Jul 03 2011 *)

Extensions

Additional comments from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 30 2001
Incorrect formulas and programs removed by R. J. Mathar, Jan 06 2011

A107395 a(n) = binomial(n+4,4)*binomial(n+6,4).

Original entry on oeis.org

15, 175, 1050, 4410, 14700, 41580, 103950, 235950, 495495, 975975, 1821820, 3248700, 5569200, 9224880, 14825700, 23197860, 35441175, 52997175, 77729190, 112015750, 158858700, 222007500, 306101250, 416830050, 561117375, 747325215, 985483800, 1287547800
Offset: 0

Views

Author

Zerinvary Lajos, May 25 2005

Keywords

Examples

			If n=0 then C(0+4,4)*C(0+6,4) = C(4,4)*C(6,4) = 1*15 = 15.
If n=9 then C(9+4,4)*C(9+6,4) = C(13,4)*C(15,4) = 715*1365 = 975975.
		

Crossrefs

Programs

  • Magma
    A107395:= func< n | Binomial(n+4,4)*Binomial(n+6,4) >;
    [A107395(n): n in [0..30]]; // G. C. Greubel, Feb 09 2025
    
  • Mathematica
    Table[Binomial[n+4,4]Binomial[n+6,4],{n,0,30}] (* Harvey P. Dale, Jun 07 2019 *)
  • SageMath
    def A107395(n): return binomial(n+4,4)*binomial(n+6,4)
    print([A107395(n) for n in range(31)]) # G. C. Greubel, Feb 09 2025

Formula

From Amiram Eldar, Sep 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 16*Pi^2 - 3946/25.
Sum_{n>=0} (-1)^n/a(n) = 1776/25 - 512*log(2)/5. (End)
G.f.: 5*(3 + 8*x + 3*x^2)/(1-x)^9. - G. C. Greubel, Feb 09 2025

Extensions

More terms from Harvey P. Dale, Jun 07 2019

A107398 a(n) = binomial(n+7, 7) * binomial(n+9, 7).

Original entry on oeis.org

36, 960, 11880, 95040, 566280, 2718144, 11042460, 39262080, 125147880, 364066560, 979945824, 2466996480, 5859116640, 13220570880, 28506855960, 59025960576, 117846969900, 227667211200, 426876021000, 778861512000, 1386019463400, 2410468632000, 4104188068500
Offset: 0

Views

Author

Zerinvary Lajos, May 25 2005

Keywords

Examples

			If n=0 then C(n+7,7)*C(n+9,7) = C(7,7)*C(9,7) = 1*36 = 36.
If n=4 then C(4+7,7)*C(4+9,7) = C(11,7)*C(13,7) = 330*1716 = 566280.
		

Crossrefs

Cf. A062196.

Programs

  • Magma
    A107398:= func< n | Binomial(n+7,7)*Binomial(n+9,7) >;
    [A107398(n): n in [0..30]]; // G. C. Greubel, Feb 07 2025
    
  • Mathematica
    a[n_] := Binomial[n + 7, 7] * Binomial[n + 9, 7]; Array[a, 25, 0] (* Amiram Eldar, Sep 01 2022 *)
  • PARI
    a(n)={binomial(n+7, 7) * binomial(n+9, 7)} \\ Andrew Howroyd, Nov 08 2019
    
  • SageMath
    def A107398(n): return binomial(n+7,7)*binomial(n+9,7)
    print([A107398(n) for n in range(31)]) # G. C. Greubel, Feb 07 2025

Formula

From Amiram Eldar, Sep 01 2022: (Start)
Sum_{n>=0} 1/a(n) = 8085*Pi^2/2 - 12767311/320.
Sum_{n>=0} (-1)^n/a(n) = 245*Pi^2/4 - 580307/960. (End)
G.f.: 12*(3 + 35*x + 105*x^2 + 105*x^3 + 35*x^4 + 3*x^5)/(1-x)^15. - G. C. Greubel, Feb 07 2025

Extensions

a(3) corrected and terms a(8) and beyond from Andrew Howroyd, Nov 08 2019

A107399 a(n) = binomial(n+8,8)*binomial(n+10,8).

Original entry on oeis.org

45, 1485, 22275, 212355, 1486485, 8281845, 38648610, 156434850, 563165460, 1837398420, 5512195260, 15380181180, 40281426900, 99773995860, 235181561670, 530311364550, 1149007956525, 2401177618125, 4855714738875, 9528883810875, 18191505457125
Offset: 0

Views

Author

Zerinvary Lajos, May 25 2005

Keywords

Examples

			If n=0 then C(0+8,8)*C(0+10,8) = C(8,8)*C(10,8) = 1*45 = 45.
If n=4 then C(7+8,8)*C(7+10,8) = C(15,8)*C(17,8) = 3003*12870 = 38648610.
		

Crossrefs

Cf. A062196.

Programs

  • Magma
    A107399:= func< n | Binomial(n+8,8)*Binomial(n+10,8) >;
    [A107399(n): n in [0..30]]; // G. C. Greubel, Feb 07 2025
    
  • Mathematica
    Table[Binomial[n+8,8]Binomial[n+10,8],{n,0,20}] (* Harvey P. Dale, Apr 03 2019 *)
  • SageMath
    def A107399(n): return binomial(n+8,8)*binomial(n+10,8)
    print([A107399(n) for n in range(31)]) # G. C. Greubel, Feb 07 2025

Formula

From Amiram Eldar, Sep 08 2022: (Start)
Sum_{n>=0} 1/a(n) = 64064*Pi^2/3 - 2987552614/14175.
Sum_{n>=0} (-1)^n/a(n) = 57237184/14175 - 262144*log(2)/45. (End)
G.f.: 45*(1 + 16*x + 70*x^2 + 112*x^3 + 70*x^4 + 16*x^5 + x^6)/(1-x)^17. - G. C. Greubel, Feb 07 2025

Extensions

More terms from Harvey P. Dale, Apr 03 2019

A105946 a(n) = C(n+3,3) * C(n+5,5).

Original entry on oeis.org

1, 24, 210, 1120, 4410, 14112, 38808, 95040, 212355, 440440, 858858, 1589952, 2815540, 4798080, 7907040, 12651264, 19718181, 30020760, 44753170, 65456160, 94093230, 133138720, 185679000, 255528000, 347358375, 466849656, 620854794, 817586560, 1066825320
Offset: 0

Views

Author

Zerinvary Lajos, Apr 27 2005

Keywords

Examples

			If n=0 then C(0+5,0)*C(0+3,3) = C(5,0)*C(3,3) = 1*1 = 1.
If n=15 then C(15+5,15)*C(15+3,3) = C(20,15)*C(18,3) = 15504*816 = 12651264.
		

Crossrefs

Cf. A062196.

Programs

Formula

G.f.: (1 + 15*x + 30*x^2 + 10*x^3)/(1-x)^9. - Colin Barker, Jan 28 2013
From Amiram Eldar, Sep 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 75*Pi^2/2 - 5905/16.
Sum_{n>=0} (-1)^n/a(n) = 160*log(2) - 5*Pi^2/4 - 4685/48. (End)
E.g.f.: (1/6!)*(720 + 16560*x + 58680*x^2 + 67320*x^3 + 32850*x^4 + 7686*x^5 + 893*x^6 + 49*x^7 + x^8)*exp(x). - G. C. Greubel, Feb 22 2025

Extensions

More terms from Colin Barker, Jan 28 2013

A105947 a(n) = C(n+4,4) * C(n+6,6).

Original entry on oeis.org

1, 35, 420, 2940, 14700, 58212, 194040, 566280, 1486485, 3578575, 8016008, 16893240, 33786480, 64574160, 118605600, 210327264, 361499985, 604167795, 984569740, 1568220500, 2446423980, 3744526500, 5632263000, 8336601000, 12157543125, 17487410031, 24834191760
Offset: 0

Views

Author

Zerinvary Lajos, Apr 27 2005

Keywords

Examples

			If n=0 then C(0+6,0)*C(0+4,4) = C(6,0)*C(4,4) = 1*1 = 1.
If n=10 then C(10+6,10)*C(10+4,4) = C(16,10)*C(14,4) = 8008*1001 = 8016008.
		

Crossrefs

Cf. A062196.

Programs

  • Magma
    A105947:= func< n | Binomial(n+4,4)*Binomial(n+6,6) >;
    [A105947(n): n in [0..40]]; // G. C. Greubel, Feb 22 2025
    
  • Mathematica
    Table[Binomial[n+6,n]Binomial[n+4,4],{n,0,30}] (* Harvey P. Dale, May 21 2014 *)
  • SageMath
    def A105947(n): return binomial(n+4,4)*binomial(n+6,6)
    print([A105947(n) for n in range(41)]) # G. C. Greubel, Feb 22 2025

Formula

G.f.: (1 + 24*x + 90*x^2 + 80*x^3 + 15*x^4)/(1-x)^11. - Colin Barker, Jan 28 2013
From Wesley Ivan Hurt, Jan 27 2022: (Start)
a(n) = (17280 + 78336*n + 152376*n^2 + 167780*n^3 + 116150*n^4 + 52983*n^5 +
16173*n^6 + 3270*n^7 + 420*n^8 + 31*n^9 + n^10)/17280.
a(n) = 11*a(n-1) - 55*a(n-2) + 165*a(n-3) - 330*a(n-4) + 462*a(n-5) - 462*a(n-6) + 330*a(n-7) - 165*a(n-8) + 55*a(n-9) - 11*a(n-10) + a(n-11). (End)
From Amiram Eldar, Sep 08 2022: (Start)
Sum_{n>=0} 1/a(n) = 224*Pi^2 - 55244/25.
Sum_{n>=0} (-1)^n/a(n) = 12*Pi^2 + 512*log(2)/5 - 4711/25. (End)

Extensions

Terms from a(8) onwards corrected by Colin Barker, Jan 28 2013
Second example corrected by Colin Barker, Jan 28 2013

A105948 a(n) = C(n+5,5) * C(n+7,7).

Original entry on oeis.org

1, 48, 756, 6720, 41580, 199584, 792792, 2718144, 8281845, 22902880, 58402344, 139007232, 311800944, 664191360, 1352103840, 2644114176, 4988699793, 9114302736, 16175074300, 27959131200, 47181033900, 77886151200, 126001769400, 200078424000, 312275179125
Offset: 0

Views

Author

Zerinvary Lajos, Apr 27 2005

Keywords

Examples

			If n=0 then C(0+7,0)*C(0+5,5) = C(7,0)*C(5,5) = 1*1 = 1.
If n=12 then C(12+7,12)*C(12+5,5) = C(19,12)*C(17,5) = 50388*6188 = 311800944.
		

Crossrefs

Cf. A062196.

Programs

  • Magma
    A105948:= func< n | Binomial(n+5,5)*Binomial(n+7,7) >;
    [A105948(n): n in [0..40]]; // G. C. Greubel, Feb 22 2025
    
  • Mathematica
    Table[Binomial[n+7,n]Binomial[n+5,5],{n,0,30}] (* Harvey P. Dale, Apr 08 2019 *)
  • SageMath
    def A105948(n): return binomial(n+5,5)*binomial(n+7,7)
    print([A105948(n) for n in range(41)]) # G. C. Greubel, Feb 22 2025

Formula

G.f.: (1 + 35*x + 210*x^2 + 350*x^3 + 175*x^4 + 21*x^5)/ (1-x)^13. - Colin Barker, Jan 29 2013
From Amiram Eldar, Sep 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 1225*Pi^2 - 1740851/144.
Sum_{n>=0} (-1)^n/a(n) = 35*Pi^2/6 - 3584*log(2)/3 + 61719/80. (End)

A107319 a(n) = C(n+8,8) * C(n+6,6).

Original entry on oeis.org

1, 63, 1260, 13860, 103950, 594594, 2774772, 11042460, 38648610, 121671550, 350414064, 935402832, 2338507080, 5521090680, 12394285200, 26606398896, 54875697723, 109181751525, 210275965900, 393175282500, 715579014150, 1270517841450, 2205030964500, 3747302149500
Offset: 0

Views

Author

Zerinvary Lajos, May 21 2005

Keywords

Examples

			If n=0 then C(0+8,8)*C(0+6,6) = C(8,8)*C(6,6) = 1*1 = 1.
If n=6 then C(6+8,8)*C(6+6,6) = C(14,8)*C(12,6) = 3003*924 = 2774772.
		

Crossrefs

Cf. A062196.

Programs

  • Magma
    A107319:= func< n | Binomial(n+6,6)*Binomial(n+8,8) >;
    [A107319(n): n in [0..40]]; // G. C. Greubel, Feb 22 2025
    
  • Mathematica
    Table[Binomial[n+8,8]Binomial[n+6,6],{n,0,20}] (* Harvey P. Dale, Sep 02 2016 *)
  • SageMath
    def A107319(n): return binomial(n+6,6)*binomial(n+8,8)
    print([A107319(n) for n in range(41)]) # G. C. Greubel, Feb 22 2025

Formula

From Amiram Eldar, Sep 08 2022: (Start)
Sum_{n>=0} 1/a(n) = 6336*Pi^2 - 76602676/1225.
Sum_{n>=0} (-1)^n/a(n) = 1365906/1225 - 80*Pi^2 - 16384*log(2)/35. (End)

Extensions

More terms from Harvey P. Dale, Sep 02 2016

A062195 Sixth (unsigned) column sequence of triangle A062139 (generalized a=2 Laguerre).

Original entry on oeis.org

1, 48, 1512, 40320, 997920, 23950080, 570810240, 13699445760, 333923990400, 8310997094400, 211930425907200, 5548723878297600, 149353151057510400, 4135933413900288000, 117874102296158208000
Offset: 0

Views

Author

Wolfdieter Lang, Jun 19 2001

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n+5)*Binomial(n+7, 7)/Factorial(5): n in [0..20]]; // G. C. Greubel, May 12 2018
  • Mathematica
    Table[(n+5)!*Binomial[n+7, 7]/5!, {n, 0, 20}] (* G. C. Greubel, May 12 2018 *)
  • PARI
    { f=24; for (n=0, 100, f*=n + 5; write("b062195.txt", n, " ", f*binomial(n + 7, 7)/120) ) } \\ Harry J. Smith, Aug 02 2009
    

Formula

E.g.f.: N(2;5, x)/(1-x)^13 with N(2;5, x) := Sum_{k=0..5} A062196(5, k)*x^k = 1+35*x+210*x^2+350*x^3+175*x^4+21*x^5.
a(n) = A062139(n+5, 5).
a(n) = (n+5)!*binomial(n+7, 7)/5!.
If we define f(n,i,x) = Sum_{k=i..n} Sum_{j=i..k} binomial(k,j) * Stirling1(n,k) * Stirling2(j,i) * x^(k-j) then a(n-5) = (-1)^(n-1)*f(n,5,-8), (n>=5). - Milan Janjic, Mar 01 2009
From Amiram Eldar, May 06 2022: (Start)
Sum_{n>=0} 1/a(n) = 1295*(Ei(1) - gamma) + 2170*e - 22813/3, where Ei(1) = A091725, gamma = A001620, and e = A001113.
Sum_{n>=0} (-1)^n/a(n) = 36575*(gamma - Ei(-1)) - 21700/e - 63455/3, where Ei(-1) = -A099285. (End)
Previous Showing 11-20 of 22 results. Next