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 1-9 of 9 results.

A107583 a(n) = 3^n - 3*n.

Original entry on oeis.org

1, 0, 3, 18, 69, 228, 711, 2166, 6537, 19656, 59019, 177114, 531405, 1594284, 4782927, 14348862, 43046673, 129140112, 387420435, 1162261410, 3486784341, 10460353140, 31381059543, 94143178758, 282429536409, 847288609368, 2541865828251, 7625597484906, 22876792454877
Offset: 0

Views

Author

Zak Seidov, May 16 2005

Keywords

Comments

a(n) is the number k such that the number m with n 3's and k 1's has digit product = digit sum = 3^n.

Examples

			Corresponding numbers m are 1, 3, 11133, 111111111111111111333, ...
		

Crossrefs

Programs

Formula

From Elmo R. Oliveira, Sep 09 2024: (Start)
G.f.: (1 - 5*x + 10*x^2)/((1 - 3*x)*(1 - x)^2).
E.g.f.: exp(x)*(exp(2*x) - 3*x).
a(n) = 5*a(n-1) - 7*a(n-2) + 3*a(n-3) for n > 2. (End)

Extensions

Corrected by Charles R Greathouse IV, Sep 08 2012

A107584 a(n) = 4^n - 4*n.

Original entry on oeis.org

1, 0, 8, 52, 240, 1004, 4072, 16356, 65504, 262108, 1048536, 4194260, 16777168, 67108812, 268435400, 1073741764, 4294967232, 17179869116, 68719476664, 274877906868, 1099511627696, 4398046511020, 17592186044328, 70368744177572, 281474976710560, 1125899906842524
Offset: 0

Views

Author

Zak Seidov, May 16 2005

Keywords

Comments

Numbers a(n) = k such that number m with n 4's and k 1's has digit product = digit sum = 4^n.

Examples

			Corresponding numbers m are 1, 4, 1111111144, ...
		

Crossrefs

Programs

Formula

From Harvey P. Dale, Oct 21 2011: (Start)
a(n) = 6*a(n-1) - 9*a(n-2) + 4*a(n-3) with a(0)=1, a(1)=0, and a(2)=8.
G.f.: (-17*x^2+6*x-1)/((x-1)^2*(4*x-1)). (End)
E.g.f.: exp(x)*(exp(3*x) - 4*x). - Elmo R. Oliveira, Sep 10 2024

Extensions

More terms from Vincenzo Librandi, Dec 16 2010
Corrected by Charles R Greathouse IV, Sep 08 2012

A198396 a(n) = 6^n - 6*n.

Original entry on oeis.org

1, 0, 24, 198, 1272, 7746, 46620, 279894, 1679568, 10077642, 60466116, 362796990, 2176782264, 13060693938, 78364164012, 470184984486, 2821109907360, 16926659444634, 101559956668308, 609359740010382, 3656158440062856, 21936950640377730, 131621703842267004, 789730223053602678
Offset: 0

Views

Author

Vincenzo Librandi, Oct 26 2011

Keywords

Crossrefs

Programs

  • Magma
    [6^n-6*n: n in [0..25]];
    
  • Mathematica
    CoefficientList[Series[(1 - 8*x + 37*x^2)/((1 - 6*x)*(1 -x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
    Table[6^n-6n,{n,0,30}] (* or *) LinearRecurrence[{8,-13,6},{1,0,24},30] (* Harvey P. Dale, Jul 25 2019 *)
  • PARI
    a(n)=6^n-6*n \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(n) = 8*a(n-1) - 13*a(n-2) + 6*a(n-3) for n > 2.
G.f.: (1-8*x+37*x^2)/((1-6*x)*(1-x)^2). - Vincenzo Librandi, Jan 04 2013
E.g.f.: exp(x)*(exp(5*x) - 6*x). - Elmo R. Oliveira, Sep 10 2024

A198397 a(n) = 7^n - 7*n.

Original entry on oeis.org

1, 0, 35, 322, 2373, 16772, 117607, 823494, 5764745, 40353544, 282475179, 1977326666, 13841287117, 96889010316, 678223072751, 4747561509838, 33232930569489, 232630513987088, 1628413597910323, 11398895185373010, 79792266297611861, 558545864083283860, 3909821048582987895
Offset: 0

Views

Author

Vincenzo Librandi, Oct 26 2011

Keywords

Crossrefs

Programs

  • Magma
    [7^n-7*n: n in [0..25]];
    
  • Mathematica
    CoefficientList[Series[(1 - 9*x + 50*x^2)/((1 - 7*x)*(1 -x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
  • PARI
    a(n)=7^n-7*n \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(n) = 9*a(n-1) - 15*a(n-2) + 7*a(n-3) for n > 2.
G.f.: (1 - 9*x + 50*x^2)/((1 - 7*x)*(1 -x)^2). - Vincenzo Librandi, Jan 04 2013
E.g.f.: exp(x)*(exp(6*x) - 7*x). - Elmo R. Oliveira, Sep 10 2024

A198398 a(n) = 8^n - 8n.

Original entry on oeis.org

1, 0, 48, 488, 4064, 32728, 262096, 2097096, 16777152, 134217656, 1073741744, 8589934504, 68719476640, 549755813784, 4398046510992, 35184372088712, 281474976710528, 2251799813685112, 18014398509481840, 144115188075855720, 1152921504606846816, 9223372036854775640
Offset: 0

Views

Author

Vincenzo Librandi, Oct 26 2011

Keywords

Crossrefs

Programs

  • Magma
    [8^n-8*n: n in [0..25]];
    
  • Mathematica
    CoefficientList[Series[(1 - 10*x + 65*x^2)/((1 - 8*x)*(1 -x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
    LinearRecurrence[{10,-17,8},{1,0,48},30] (* Harvey P. Dale, Mar 13 2023 *)
  • PARI
    a(n)=8^n-8*n \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(n) = 10*a(n-1) - 17*a(n-2) + 8*a(n-3) for n > 2.
G.f.: (1 - 10*x + 65*x^2)/((1 - 8*x)*(1 -x)^2). - Vincenzo Librandi, Jan 04 2013
E.g.f.: exp(x)*(exp(7*x) - 8*x). - Elmo R. Oliveira, Sep 10 2024

A198399 a(n) = 9^n - 9*n.

Original entry on oeis.org

1, 0, 63, 702, 6525, 59004, 531387, 4782906, 43046649, 387420408, 3486784311, 31381059510, 282429536373, 2541865828212, 22876792454835, 205891132094514, 1853020188851697, 16677181699666416, 150094635296998959, 1350851717672991918, 12157665459056928621, 109418989131512359020
Offset: 0

Views

Author

Vincenzo Librandi, Oct 26 2011

Keywords

Crossrefs

Programs

  • Magma
    [9^n-9*n: n in [0..25]];
    
  • Mathematica
    CoefficientList[Series[(1 - 11*x + 82*x^2)/((1 - 9*x)*(1 - x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
  • PARI
    a(n)=9^n-9*n \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(0)=1, a(1)=0, a(2)=63, a(n) = 11*a(n-1) - 19*a(n-2) + 9*a(n-3).
G.f.: (1 - 11*x + 82*x^2)/((1 - 9*x)*(1 - x)^2). - Vincenzo Librandi, Jan 04 2013
E.g.f.: exp(x)*(exp(8*x) - 9*x). - Elmo R. Oliveira, Sep 09 2024

A198400 a(n) = 10^n - 10*n.

Original entry on oeis.org

1, 0, 80, 970, 9960, 99950, 999940, 9999930, 99999920, 999999910, 9999999900, 99999999890, 999999999880, 9999999999870, 99999999999860, 999999999999850, 9999999999999840, 99999999999999830, 999999999999999820, 9999999999999999810, 99999999999999999800, 999999999999999999790
Offset: 0

Views

Author

Vincenzo Librandi, Oct 26 2011

Keywords

Crossrefs

Programs

  • Magma
    [10^n-10*n: n in [0..25]];
    
  • Mathematica
    CoefficientList[Series[(1-12*x+101*x^2)/((1-10*x)*(1-x)^2),{x,0,40}],x] (* Vincenzo Librandi, Jul 06 2012 *)
  • PARI
    a(n)=10^n-10*n \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n > 2.
G.f.: (1-12*x+101*x^2)/((1-10*x)*(1-x)^2). - Vincenzo Librandi, Jul 06 2012
E.g.f.: exp(x)*(exp(9*x) - 10*x). - Elmo R. Oliveira, Aug 29 2024

A221907 a(n) = 5^n + 5*n.

Original entry on oeis.org

1, 10, 35, 140, 645, 3150, 15655, 78160, 390665, 1953170, 9765675, 48828180, 244140685, 1220703190, 6103515695, 30517578200, 152587890705, 762939453210, 3814697265715, 19073486328220, 95367431640725, 476837158203230, 2384185791015735, 11920928955078240, 59604644775390745
Offset: 0

Views

Author

Vincenzo Librandi, Mar 02 2013

Keywords

Crossrefs

Programs

  • Magma
    [5^n + 5*n: n in [0..30]];
    
  • Magma
    I:=[1, 10, 35]; [n le 3 select I[n] else 7*Self(n-1)-11*Self(n-2)+5*Self(n-3): n in [1..30]];
    
  • Mathematica
    Table[(5^n + 5 n), {n, 0, 30}] (* or *) CoefficientList[Series[(1 + 3 x - 24 x^2)/((1 - x)^2 (1 - 5 x)), {x, 0, 30}], x]
    LinearRecurrence[{7,-11,5},{1,10,35},30] (* Harvey P. Dale, Jul 23 2013 *)
  • PARI
    a(n)=5^n+5*n \\ Charles R Greathouse IV, Apr 18 2013

Formula

G.f.: (1+3*x-24*x^2)/((1-x)^2*(1-5*x)).
a(n) = 7*a(n-1) - 11*a(n-2) + 5*a(n-3).
a(n) = A176916(n) - 1.
a(n) = 5*A362555(n) for n > 0. - Hugo Pfoertner, Mar 01 2024
E.g.f.: exp(x)*(exp(4*x) + 5*x). - Elmo R. Oliveira, Sep 10 2024

A268414 a(n) = 5*a(n-1) - 2*n for n > 0, a(0) = 1.

Original entry on oeis.org

1, 3, 11, 49, 237, 1175, 5863, 29301, 146489, 732427, 3662115, 18310553, 91552741, 457763679, 2288818367, 11444091805, 57220458993, 286102294931, 1430511474619, 7152557373057, 35762786865245, 178813934326183, 894069671630871, 4470348358154309, 22351741790771497, 111758708953857435
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 04 2016

Keywords

Comments

In general, the ordinary generating function for the recurrence relation b(n) = k*b(n - 1) - m*n, with n > 0 and b(0)=1, is (1 - (m + 2)*x + x^2)/((1 - x)^2*(1 - k*x)). This recurrence gives the closed form b(n) = ((k^2 - k*(m + 2) + 1)*k^n + m*((k - 1)*n + k))/(k - 1)^2.

Crossrefs

Programs

  • Magma
    [(4*n + 3*5^n + 5)/8: n in [0..30]]; // Vincenzo Librandi, Feb 06 2016
  • Mathematica
    Table[(4 n + 3 5^n + 5)/8, {n, 0, 23}]
    LinearRecurrence[{7, -11, 5}, {1, 3, 11}, 24]
  • PARI
    Vec((1-4*x+x^2)/((1-x)^2*(1-5*x)) + O(x^100)) \\ Altug Alkan, Feb 04 2016
    

Formula

G.f.: (1 - 4*x + x^2)/((1 - x)^2*(1 - 5*x)).
a(n) = (4*n + 3*5^n + 5)/8.
Sum_{n>=0} 1/a(n) = 1.449934283402232875...
Lim_{n -> oo} a(n + 1)/a(n) = 5.
From Elmo R. Oliveira, Sep 10 2024: (Start)
E.g.f.: exp(x)*(3*exp(4*x) + 4*x + 5)/8.
a(n) = 7*a(n-1) - 11*a(n-2) + 5*a(n-3) for n > 2. (End)

Extensions

a(24)-a(25) from Elmo R. Oliveira, Sep 10 2024
Showing 1-9 of 9 results.