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.

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A189749 a(1)=5, a(2)=5, a(n)=5*a(n-1) + 5*a(n-2).

Original entry on oeis.org

5, 5, 50, 275, 1625, 9500, 55625, 325625, 1906250, 11159375, 65328125, 382437500, 2238828125, 13106328125, 76725781250, 449160546875, 2629431640625, 15392960937500, 90111962890625, 527524619140625, 3088182910156250, 18078537646484375, 105833602783203125
Offset: 1

Views

Author

Harvey P. Dale, Apr 26 2011

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5,5},{5,5},40]
  • Maxima
    a[1]:5$ a[2]:5$ a[n]:=5*a[n-1]+5*a[n-2]$ makelist(a[n], n, 1, 23); /* Bruno Berselli, May 24 2011 */

Formula

G.f.: 5*x*(1-4*x)/(1-5*x-5*x^2). - Bruno Berselli, May 24 2011
a(n) = 5*A188168(n). - R. J. Mathar, Feb 13 2020

A189737 a(1)=3, a(2)=3, a(n)=3*a(n-1) + 3*a(n-2).

Original entry on oeis.org

3, 3, 18, 63, 243, 918, 3483, 13203, 50058, 189783, 719523, 2727918, 10342323, 39210723, 148659138, 563609583, 2136806163, 8101247238, 30714160203, 116446222323, 441481147578, 1673782109703, 6345789771843, 24058715644638, 91213516249443, 345816695682243
Offset: 1

Views

Author

Harvey P. Dale, Apr 26 2011

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{3,3},{3,3},40]
  • Maxima
    a[1]:3$ a[2]:3$ a[n]:=3*a[n-1]+3*a[n-2]$ makelist(a[n], n, 1, 26); /* Bruno Berselli, May 24 2011 */

Formula

G.f.: 3*x*(1-2*x)/(1-3*x-3*x^2). - Bruno Berselli, May 24 2011

A189746 a(1)=5, a(2)=2, a(n) = 5*a(n-1) + 2*a(n-2).

Original entry on oeis.org

5, 2, 20, 104, 560, 3008, 16160, 86816, 466400, 2505632, 13460960, 72316064, 388502240, 2087143328, 11212721120, 60237892256, 323614903520, 1738550302112, 9339981317600, 50177007192224, 269564998596320, 1448179007366048, 7780025034022880, 41796483184846496
Offset: 1

Views

Author

Harvey P. Dale, Apr 26 2011

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5,2},{5,2},40]
  • Maxima
    a[1]:5$ a[2]:2$ a[n]:=5*a[n-1]+2*a[n-2]$ makelist(a[n], n, 1, 24); /* Bruno Berselli, May 24 2011 */

Formula

G.f.: x*(5-23*x)/(1-5*x-2*x^2). - Bruno Berselli, May 24 2011

A189747 a(1)=5, a(2)=3, a(n)=5*a(n-1) + 3*a(n-2).

Original entry on oeis.org

5, 3, 30, 159, 885, 4902, 27165, 150531, 834150, 4622343, 25614165, 141937854, 786531765, 4358472387, 24151957230, 133835203311, 741631888245, 4109665051158, 22773220920525, 126195099756099, 699295161542070, 3875061106978647, 21473191019519445
Offset: 1

Views

Author

Harvey P. Dale, Apr 26 2011

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5,3},{5,3},40]
  • Maxima
    a[1]:5$ a[2]:3$ a[n]:=5*a[n-1]+3*a[n-2]$ makelist(a[n], n, 1, 23); /* Bruno Berselli, May 24 2011 */

Formula

G.f.: x*(5-22*x)/(1-5*x-3*x^2). - Bruno Berselli, May 24 2011

A189748 a(n) = 5*a(n-1) + 4*a(n-2) with a(1)=5, a(2)=4.

Original entry on oeis.org

5, 4, 40, 216, 1240, 7064, 40280, 229656, 1309400, 7465624, 42565720, 242691096, 1383718360, 7889356184, 44981654360, 256465696536, 1462255100120, 8337138286744, 47534711834200, 271022112317976, 1545249408926680, 8810335493905304, 50232675105233240
Offset: 1

Views

Author

Harvey P. Dale, Apr 26 2011

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{5,4},{5,4},40]
  • Maxima
    a[1]:5$ a[2]:4$ a[n]:=5*a[n-1]+4*a[n-2]$ makelist(a[n], n, 1, 23); /* Bruno Berselli, May 24 2011 */

Formula

G.f.: x*(5-21*x)/(1-5*x-4*x^2). - Bruno Berselli, May 24 2011

A014334 Exponential convolution of Fibonacci numbers with themselves.

Original entry on oeis.org

0, 0, 2, 6, 22, 70, 230, 742, 2406, 7782, 25190, 81510, 263782, 853606, 2762342, 8939110, 28927590, 93611622, 302933606, 980313702, 3172361830, 10265978470, 33221404262, 107506722406, 347899061862, 1125825013350, 3643246274150, 11789792601702
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(2^n*Lucas(n) -2)/5: n in [0..40]]; // Vincenzo Librandi, Jul 15 2018
    
  • Mathematica
    LinearRecurrence[{3,2,-4}, {0,0,2}, 30] (* Harvey P. Dale, Oct 24 2015 *)
    Table[(2^n LucasL[n] -2)/5, {n,0,100}] (* Vladimir Reshetnikov, May 18 2016 *)
  • PARI
    a(n)=if(n<1,0,sum(k=0,n-1,fibonacci(k)*2^k))
    
  • SageMath
    [(2^n*lucas_number2(n,1,-1) -2)/5 for n in range(41)] # G. C. Greubel, Jan 06 2023

Formula

From Benoit Cloitre, May 29 2003: (Start)
a(n) = 3*a(n-1) + 2*a(n-2) - 4*a(n-3), a(0)=0, a(1)=0, a(2)=2.
a(n) = Sum_{k=0..n-1} 2^k*Fibonacci(k) for n > 0.
a(n) = (-2 + ((1+sqrt(5))^n + (1-sqrt(5))^n))/5. (End)
a(n) = Sum_{k=0..n} Fibonacci(k)*Fibonacci(n-k)*binomial(n, k). - Benoit Cloitre, May 11 2005
From R. J. Mathar, Sep 29 2010: (Start)
a(n) = 2*A014335(n).
G.f.: 2*x^2/((1-x)*(1-2*x-4*x^2)).
a(n) = Sum_{k=1..n-1} A103435(k). (End)
a(n) = (2^n*A000032(n) - 2)/5. - Vladimir Reshetnikov, May 18 2016
E.g.f.: 2*(cosh(sqrt(5)*x)-1)*exp(x)/5. - Ilya Gutkovskiy, May 18 2016
a(n) = ((Sum_{k=0..n} Lucas(k)*Lucas(n-k)*binomial(n, k)) - 4)/5 (Wall, 1986). - Amiram Eldar, Jan 27 2022

A006483 a(n) = Fibonacci(n)*2^n + 1.

Original entry on oeis.org

1, 3, 5, 17, 49, 161, 513, 1665, 5377, 17409, 56321, 182273, 589825, 1908737, 6176769, 19988481, 64684033, 209321985, 677380097, 2192048129, 7093616641, 22955425793, 74285318145, 240392339457, 777925951489, 2517421260801, 8146546327553, 26362777698305
Offset: 0

Views

Author

Dennis S. Kluk (mathemagician(AT)ameritech.net)

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Equals A103435 + 1.

Programs

Formula

G.f.: -(-1+6*x^2)/((1-x)*(1-2*x-4*x^2)).

Extensions

G.f. in Formula field corrected by Vincenzo Librandi, Jun 09 2013

A269991 Decimal expansion of Sum_{n >= 1} 2^(1-n)/Fibonacci(n).

Original entry on oeis.org

1, 6, 8, 4, 8, 1, 3, 1, 4, 4, 4, 8, 9, 5, 7, 6, 0, 9, 6, 3, 1, 6, 5, 5, 4, 3, 3, 7, 3, 8, 0, 0, 7, 8, 2, 3, 0, 2, 3, 7, 0, 6, 3, 8, 8, 2, 4, 5, 7, 0, 8, 6, 8, 2, 0, 9, 4, 3, 1, 7, 6, 1, 8, 8, 5, 9, 5, 0, 5, 6, 0, 0, 2, 8, 0, 4, 9, 4, 5, 4, 9, 8, 9, 1, 0, 8
Offset: 1

Views

Author

Clark Kimberling, Mar 12 2016

Keywords

Examples

			1.684813144489576096316554337380078230...
		

Crossrefs

Programs

  • Mathematica
    x = N[Sum[2^(1 - n)/Fibonacci[n], {n, 1, 500}], 100]
    RealDigits[x][[1]]
  • PARI
    suminf(n=1, 2^(1-n)/fibonacci(n)) \\ Michel Marcus, Feb 01 2021

Formula

Equals Sum_{n>=0} 1/A063727(n) = Sum_{n>=1} 1/A085449(n) = 2 * Sum_{n>=1} 1/A103435(n) = 4 * Sum_{n>=1} 1/A209084(n). - Amiram Eldar, Feb 01 2021

A086344 a(n) = -2*a(n-1) + 4*a(n-2), a(0) = 1, a(1) = 0.

Original entry on oeis.org

1, 0, 4, -8, 32, -96, 320, -1024, 3328, -10752, 34816, -112640, 364544, -1179648, 3817472, -12353536, 39976960, -129368064, 418643968, -1354760192, 4384096256, -14187233280, 45910851584, -148570636288, 480784678912, -1555851902976, 5034842521600, -16293092655104
Offset: 0

Views

Author

Paul Barry, Jul 17 2003

Keywords

Comments

Inverse binomial transform of (1,1,5,5,25,25,.....).
The absolute values are the constant terms of the reduction by x^2->x+1 of the polynomial p(n,x) given for d=sqrt(x+1) by p(n,x)=((x+d)^n-(x-d)^n)/(2d), for n>=1. The coefficient of x under this reduction is given by A103435. See A192232 for a discussion of reduction. - Clark Kimberling, Jun 29 2011

Programs

  • Maple
    seq((-2)^n * combinat:-fibonacci(n-1), n = 0 .. 100); # Robert Israel, Oct 02 2014
  • Mathematica
    LinearRecurrence[{-2,4},{1,0},40] (* Harvey P. Dale, Oct 10 2018 *)

Formula

G.f.: (1+2*x)/((1+(1+sqrt(5))*x)(1+(1-sqrt(5))*x)) = ( -1-2*x ) / ( -1-2*x+4*x^2 ).
E.g.f.: exp(-x)*(cosh(sqrt(5)*x)+sinh(sqrt(5)*x)/sqrt(5)).
a(n)=(sqrt(5)-1)^n*(sqrt(5)/10+1/2)+(-sqrt(5)-1)^n*(1/2-sqrt(5)/10).
(-1)^n*a(n) = A063727(n) - 2*A063727(n-1). - R. J. Mathar, Jul 19 2012
(-1)^n*a(n) = sum(k=0..n, binomial(n,k)*(F(n+1)-F(n))), F(n) Fibonacci number A000045. - Peter Luschny, Oct 01 2014
a(n) = (-2)^n *A000045(n-1). - Robert Israel, Oct 02 2014

A209084 a(n) = 2*a(n-1) + 4*a(n-2) with n>1, a(0)=0, a(1)=4.

Original entry on oeis.org

0, 4, 8, 32, 96, 320, 1024, 3328, 10752, 34816, 112640, 364544, 1179648, 3817472, 12353536, 39976960, 129368064, 418643968, 1354760192, 4384096256, 14187233280, 45910851584, 148570636288, 480784678912, 1555851902976, 5034842521600, 16293092655104
Offset: 0

Views

Author

Seiichi Kirikami, Mar 06 2012

Keywords

Comments

a(n)/A063727(n) are convergents for A134972.
Abs(Sum_{i=0..n} C(n,n-i)*a(i)-(sqrt(5)-1)* A033887(n))->0. - Seiichi Kirikami, Jan 20 2016

References

  • E. W. Cheney, Introduction to Approximation Theory, McGraw-Hill, Inc., 1966.

Crossrefs

Cf. A086344 (this sequence with signs).

Programs

  • Magma
    I:=[0,4]; [n le 2 select I[n] else 2*Self(n-1)+4*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Jan 16 2016
  • Mathematica
    RecurrenceTable[{a[n]==2*a[n-1]+4*a[n-2], a[0]==0, a[1]==4}, a, {n, 30}]
    LinearRecurrence[{2, 4}, {0, 4}, 40] (* Vincenzo Librandi, Jan 16 2016 *)
  • PARI
    concat(0, Vec(4*x/(1-2*x-4*x^2) + O(x^40))) \\ Michel Marcus, Jan 16 2016
    

Formula

a(n) = (2/sqrt(5))*((1+sqrt(5))^n-(1-sqrt(5))^n).
G.f.: 4*x/(1-2*x-4*x^2). - Bruno Berselli, Mar 08 2012
a(n) = 4*A085449(n) = 2*A103435(n). - Bruno Berselli, Mar 08 2012
Sum_{n>=1} 1/a(n) = (1/4) * A269991. - Amiram Eldar, Feb 01 2021
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