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 1-7 of 7 results.

A166525 a(n) = 10*n - a(n-1), with n>1, a(1)=1.

Original entry on oeis.org

1, 19, 11, 29, 21, 39, 31, 49, 41, 59, 51, 69, 61, 79, 71, 89, 81, 99, 91, 109, 101, 119, 111, 129, 121, 139, 131, 149, 141, 159, 151, 169, 161, 179, 171, 189, 181, 199, 191, 209, 201, 219, 211, 229, 221, 239, 231, 249, 241, 259, 251, 269, 261, 279, 271, 289
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

  • Magma
    [n eq 1 select 1 else 10*n-Self(n-1): n in [1..80]]; // Vincenzo Librandi, Sep 13 2013
    
  • Mathematica
    CoefficientList[Series[(1 +18 x -9 x^2)/((1+x) (1-x)^2), {x,0,80}], x] (* Vincenzo Librandi, Sep 13 2013 *)
    LinearRecurrence[{1,1,-1}, {1,19,11}, 50] (* G. C. Greubel, May 16 2016 *)
  • SageMath
    def A166525(n): return 5*n - 4 + 13*((n+1)%2)
    [A166525(n) for n in range(1, 101)] # G. C. Greubel, Aug 04 2024

Formula

G.f.: x*(1+18*x-9*x^2) / ( (1+x)*(1-x)^2 ). - R. J. Mathar, Mar 08 2011
From G. C. Greubel, May 16 2016: (Start)
E.g.f.: (1/2)*(13*exp(-x) + 5*(1 + 2*x)*exp(x) - 18).
a(n) = a(n-1) + a(n-2) - a(n-3). (End)
Sum_{n>=1} (-1)^(n+1)/a(n) = 1/9 + sqrt(5+2*sqrt(5))*Pi/10. - Amiram Eldar, Feb 24 2023
a(n) = (1/2)*(10*n + 5 + 13*(-1)^n). - G. C. Greubel, Aug 04 2024

A166520 a(n) = (10*n + 11*(-1)^n + 5)/4.

Original entry on oeis.org

1, 9, 6, 14, 11, 19, 16, 24, 21, 29, 26, 34, 31, 39, 36, 44, 41, 49, 46, 54, 51, 59, 56, 64, 61, 69, 66, 74, 71, 79, 76, 84, 81, 89, 86, 94, 91, 99, 96, 104, 101, 109, 106, 114, 111, 119, 116, 124, 121, 129, 126, 134, 131, 139, 136, 144, 141, 149, 146, 154, 151, 159
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

Formula

a(n) = 5*n - a(n-1) for n > 1, with a(1) = 1.
G.f. x*(1+8*x-4*x^2) / ( (1+x)*(1-x)^2 ). - R. J. Mathar, Mar 08 2011
From G. C. Greubel, May 16 2016: (Start)
E.g.f.: (5*(1 + 2*x)*exp(x) + 11*exp(-x) - 16)/4.
a(n) = a(n-1) + a(n-2) - a(n-3). (End)

A166521 a(n) = (6*n + 7*(-1)^n + 3)/2.

Original entry on oeis.org

1, 11, 7, 17, 13, 23, 19, 29, 25, 35, 31, 41, 37, 47, 43, 53, 49, 59, 55, 65, 61, 71, 67, 77, 73, 83, 79, 89, 85, 95, 91, 101, 97, 107, 103, 113, 109, 119, 115, 125, 121, 131, 127, 137, 133, 143, 139, 149, 145, 155, 151, 161, 157, 167, 163, 173, 169, 179, 175, 185
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

Formula

a(n) = 6*n - a(n-1), for n > 1, with a(1) = 1.
G.f.: x*(1+10*x-5*x^2) / ((1+x)*(1-x)^2). - R. J. Mathar, Mar 08 2011
From G. C. Greubel, May 16 2016: (Start)
E.g.f.: (1/2)*(7*exp(-x) + 3*(1+2*x)*exp(x) -10).
a(n) = a(n-1) + a(n-2) - a(n-3). (End)
Sum_{n>=1} (-1)^(n+1)/a(n) = 1/5 + Pi/(2*sqrt(3)). - Amiram Eldar, Feb 24 2023

A166522 a(n) = 7*n - a(n-1), with a(1) = 1.

Original entry on oeis.org

1, 13, 8, 20, 15, 27, 22, 34, 29, 41, 36, 48, 43, 55, 50, 62, 57, 69, 64, 76, 71, 83, 78, 90, 85, 97, 92, 104, 99, 111, 106, 118, 113, 125, 120, 132, 127, 139, 134, 146, 141, 153, 148, 160, 155, 167, 162, 174, 169, 181, 176, 188, 183, 195, 190, 202, 197, 209, 204
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

  • Magma
    A166522:= func< n | ( 7*n -5 +17*((n+1) mod 2) )/2 >;
    [A166522(n): n in [1..100]]; // G. C. Greubel, Aug 03 2024
    
  • Mathematica
    RecurrenceTable[{a[1]==1,a[n]==7n-a[n-1]},a,{n,60}] (* or *) LinearRecurrence[{1,1,-1},{1,13,8},60] (* Harvey P. Dale, Jun 07 2012 *)
  • SageMath
    def A166522(n): return ( 7*n -5 +17*((n+1)%2) )//2
    [A166522(n) for n in range(1,101)] # G. C. Greubel, Aug 03 2024

Formula

G.f.: x*(1+12*x-6*x^2) / ( (1+x)*(1-x)^2 ). - R. J. Mathar, Mar 08 2011
a(n) = a(n-1) + a(n-2) - a(n-3), a(1)=1, a(2)=13, a(3)=8. - Harvey P. Dale, Jun 07 2012
E.g.f.: (1/4)*(17*exp(-x) + 7*(1 + 2*x)*exp(x) - 24). - G. C. Greubel, May 16 2016
a(n) = (1/4)*(14*n + 7 + 17*(-1)^n). - G. C. Greubel, Aug 03 2024

A166523 a(n) = 8*n - a(n-1), with n>1, a(1)=1.

Original entry on oeis.org

1, 15, 9, 23, 17, 31, 25, 39, 33, 47, 41, 55, 49, 63, 57, 71, 65, 79, 73, 87, 81, 95, 89, 103, 97, 111, 105, 119, 113, 127, 121, 135, 129, 143, 137, 151, 145, 159, 153, 167, 161, 175, 169, 183, 177, 191, 185, 199, 193, 207, 201, 215, 209, 223, 217, 231, 225, 239, 233
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

  • Magma
    [n eq 1 select 1 else 8*n-Self(n-1): n in [1..70]]; // Vincenzo Librandi, Sep 13 2013
    
  • Mathematica
    CoefficientList[Series[(1 +14 x -7 x^2)/((1+x) (1-x)^2), {x,0,60}], x] (* Vincenzo Librandi, Sep 13 2013 *)
  • SageMath
    def A166523(n): return 4*n - 3 + 10*((n+1)%2)
    [A166523(n) for n in range(1,101)] # G. C. Greubel, Aug 03 2024

Formula

G.f.: x*(1+14*x-7*x^2) / ( (1+x)*(1-x)^2 ). - R. J. Mathar, Mar 08 2011
From G. C. Greubel, May 16 2016: (Start)
E.g.f.: 5*exp(-x) + 2*(1 + 2*x)*exp(x) - 7.
a(n) = a(n-1) + a(n-2) - a(n-3). (End)
Sum_{n>=1} (-1)^(n+1)/a(n) = 1/7 + (1/8 + 1/(4*sqrt(2)))*Pi. - Amiram Eldar, Feb 24 2023
a(n) = 4*n + 2 + 5*(-1)^n. - G. C. Greubel, Aug 03 2024

A166524 a(n) = 9*n - a(n-1), with n>1, a(1)=1.

Original entry on oeis.org

1, 17, 10, 26, 19, 35, 28, 44, 37, 53, 46, 62, 55, 71, 64, 80, 73, 89, 82, 98, 91, 107, 100, 116, 109, 125, 118, 134, 127, 143, 136, 152, 145, 161, 154, 170, 163, 179, 172, 188, 181, 197, 190, 206, 199, 215, 208, 224, 217, 233, 226, 242, 235, 251, 244, 260, 253
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

  • Magma
    [n eq 1 select 1 else 9*n-Self(n-1): n in [1..80]]; // Vincenzo Librandi, Sep 13 2013
    
  • Mathematica
    CoefficientList[Series[(1 +16 x -8 x^2)/((1+x) (1-x)^2), {x,0,80}], x] (* Vincenzo Librandi, Sep 13 2013 *)
    LinearRecurrence[{1,1,-1},{1,17,10},60] (* Harvey P. Dale, Dec 24 2014 *)
  • SageMath
    def A166524(n): return (9*n - 7 + 23*((n+1)%2))//2
    [A166524(n) for n in range(1, 101)] # G. C. Greubel, Aug 04 2024

Formula

G.f.: x*(1+16*x-8*x^2) / ( (1+x)*(1-x)^2 ). - R. J. Mathar, Mar 08 2011
From G. C. Greubel, May 16 2016: (Start)
E.g.f.: (1/4)*(23*exp(-x) + 9*(1 + 2*x)*exp(x) - 32).
a(n) = a(n-1) + a(n-2) - a(n-3). (End)
Sum_{n>=1} (-1)^(n+1)/a(n) = 1/8 + cot(Pi/9)*Pi/9. - Amiram Eldar, Feb 24 2023
a(n) = (1/4)*(18*n + 9 + 23*(-1)^n). - G. C. Greubel, Aug 04 2024

A166539 a(n) = (10*n + 7*(-1)^n + 5)/4.

Original entry on oeis.org

2, 8, 7, 13, 12, 18, 17, 23, 22, 28, 27, 33, 32, 38, 37, 43, 42, 48, 47, 53, 52, 58, 57, 63, 62, 68, 67, 73, 72, 78, 77, 83, 82, 88, 87, 93, 92, 98, 97, 103, 102, 108, 107, 113, 112, 118, 117, 123, 122, 128, 127, 133, 132, 138, 137, 143, 142, 148, 147, 153, 152, 158
Offset: 1

Views

Author

Vincenzo Librandi, Oct 16 2009

Keywords

Crossrefs

Programs

  • Magma
    [5*n/2 + (5+7*(-1)^n)/4: n in [1..70]]; // Vincenzo Librandi, May 15 2013
    
  • Mathematica
    RecurrenceTable[{a[1]==2,a[n]==5n-a[n-1]},a[n],{n,70}] (* or *) LinearRecurrence[{1,1,-1},{2,8,7},70] (* Harvey P. Dale, Jun 29 2011 *)
  • SageMath
    def A166539(n): return (5*n - 1 + 7*((n+1)%2))//2
    [A166539(n) for n in range(1, 101)] # G. C. Greubel, Aug 04 2024

Formula

a(n) = 5*n - a(n-1), n>=2.
From Harvey P. Dale, Jun 29 2011: (Start)
a(n) = a(n-1) + a(n-2) - a(n-3), n>=4.
G.f.: x*(2+3*x*(2-x))/((1-x)^2*(1+x)). (End)
From G. C. Greubel, May 16 2016: (Start)
E.g.f.: (1/4)*(5*(1 + 2*x)*exp(x) + 7*exp(-x) - 12).
a(n) = a(n-1) + a(n-2) - a(n-3). (End)
Sum_{n>=1} (-1)^(n+1)/a(n) = 1/3 + sqrt((5-2*sqrt(5))/5)*Pi/5. - Amiram Eldar, Feb 24 2023
a(n) = A166520(n) - (-1)^n. - G. C. Greubel, Aug 04 2024
Showing 1-7 of 7 results.