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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A134489 a(n) = Fibonacci(5*n + 2).

Original entry on oeis.org

1, 13, 144, 1597, 17711, 196418, 2178309, 24157817, 267914296, 2971215073, 32951280099, 365435296162, 4052739537881, 44945570212853, 498454011879264, 5527939700884757, 61305790721611591, 679891637638612258
Offset: 0

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Author

Artur Jasinski, Oct 28 2007

Keywords

Comments

The o.g.f. of {F(m*n + 2)}_{n>=0}, for m = 1, 2, ..., is
G(m,x) = (1 + F(m - 2)*x) / (1 - L(m)*x + (-1)^m*x^2), with F = A000045 and F(-1) = 1, and L = A000032. - Wolfdieter Lang, Feb 06 2023

Crossrefs

Programs

  • Magma
    [Fibonacci(5*n+2): n in [0..50]]; // Vincenzo Librandi, Apr 20 2011
  • Mathematica
    Table[Fibonacci[5n + 2], {n, 0, 30}]
    LinearRecurrence[{11,1},{1,13},20] (* Harvey P. Dale, May 05 2022 *)

Formula

From R. J. Mathar, Jul 04 2011: (Start)
G.f.: (-1-2*x) / (-1 + 11*x + x^2).
a(n) = 2*A049666(n) + A049666(n+1). (End)
a(n) = A000045(A016873(n)). - Michel Marcus, Nov 05 2013

A360958 Decimal expansion of Sum_{i>=1} 1/Fibonacci(3*i).

Original entry on oeis.org

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

Views

Author

Kevin Ryde, Feb 28 2023

Keywords

Comments

Sum of reciprocals of the even Fibonacci numbers, so Sum_{i>=1} 1/A014445(i)

Examples

			.66350213893302819713588109594999329...
		

Crossrefs

Formula

Equals A079586 - A360957.

A020712 Pisot sequences E(5,8), P(5,8).

Original entry on oeis.org

5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155, 165580141
Offset: 0

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Author

Keywords

Comments

Pisano period lengths: 1, 3, 8, 6, 20, 24, 16, 12, 24, 60, 10, 24, 28, 48, 40, 24, 36, 24, 18, 60,.. - R. J. Mathar, Aug 10 2012

Crossrefs

Subsequence of A020701 and hence A020695, A000045. See A008776 for definitions of Pisot sequences.
Trisections: A015448, A014445, A033887.

Programs

Formula

a(n) = Fib(n+5). a(n) = a(n-1) + a(n-2).
O.g.f.: (5+3x)/(1-x-x^2). a(n)=A020701(n+1). - R. J. Mathar, May 28 2008
a(n) = (2^(-1-n)*((1-sqrt(5))^n*(-11+5*sqrt(5))+(1+sqrt(5))^n*(11+5*sqrt(5))))/sqrt(5). - Colin Barker, Jun 05 2016

A087579 a(n) = (1/6)*Sum_{k=0..n} binomial(n,k)*Fibonacci(k)*6^k.

Original entry on oeis.org

1, 8, 93, 976, 10505, 112344, 1203397, 12885152, 137979729, 1477507240, 15821470061, 169419470448, 1814178395353, 19426591805816, 208023907911765, 2227562425662784, 23853192734743457, 255424852222168392, 2735141407084907389, 29288451971122142480
Offset: 0

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Author

Benoit Cloitre, Oct 25 2003

Keywords

Crossrefs

Programs

Formula

a(n) = 8*a(n-1) + 29*a(n-2).
G.f.: 1 / (-29*x^2-8*x+1). - Colin Barker, Aug 08 2013

Extensions

More terms from Colin Barker, Aug 08 2013

A087584 a(n) = (1/7)*Sum_{k=0..n} binomial(n,k)*Fibonacci(k)*7^k.

Original entry on oeis.org

1, 9, 122, 1467, 18205, 223992, 2762333, 34044669, 419657674, 5172750495, 63760719089, 785929242096, 9687552661513, 119411072879553, 1471889315038010, 18142857823403763, 223633182327192277, 2756555811704284776, 33977962780753446341, 418820453306656692885
Offset: 0

Views

Author

Benoit Cloitre, Oct 25 2003

Keywords

Crossrefs

Formula

a(n) = 9*a(n-1) + 41*a(n-2).
G.f.: 1 / (-41*x^2-9*x+1). - Colin Barker, Aug 08 2013

Extensions

More terms from Colin Barker, Aug 08 2013

A138859 Smallest prime factor of Fibonacci(3n)-1, i.e., A020639(A000071(3n)).

Original entry on oeis.org

7, 3, 11, 3, 3, 5, 199, 13, 13, 3, 37, 3, 3, 89, 5, 11, 7, 3, 59, 3, 3, 11, 11, 37, 37, 3, 370248451, 3, 3, 139, 13, 5, 5, 3, 5, 3, 3, 59, 709, 557, 127, 3, 11, 3, 3, 5, 9375829, 73, 7, 3, 29, 3, 3, 2789, 5, 11, 47, 3, 13, 3, 3, 11, 11, 13, 7, 3, 809, 3, 3, 953, 47927441, 5, 5
Offset: 2

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Author

M. F. Hasler, Apr 05 2008

Keywords

Comments

F(n)-1 is even if n is not a multiple of 3.

Crossrefs

Programs

  • Mathematica
    Table[FactorInteger[Fibonacci[3n]-1][[1,1]],{n,2,80}] (* Harvey P. Dale, Aug 08 2017 *)
  • PARI
    A138859(n)=factor(fibonacci(3*n)-1)[1,1] /* A138859 is defined only for n>1 ! */

Formula

a(n) = A020639(A000071(3n)).

A269500 a(n) = Fibonacci(10*n).

Original entry on oeis.org

0, 55, 6765, 832040, 102334155, 12586269025, 1548008755920, 190392490709135, 23416728348467685, 2880067194370816120, 354224848179261915075, 43566776258854844738105, 5358359254990966640871840, 659034621587630041982498215, 81055900096023504197206408605
Offset: 0

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Author

Ilya Gutkovskiy, Mar 03 2016

Keywords

Comments

More generally, the ordinary generating function for the Fibonacci(k*n) is F(k)*x/(1 - L(k)*x + (-1)^k*x^2), where F(k) is the k-th Fibonacci number (A000045), L(k) is the k-th Lucas number (A000032), or (phi^k - (-1/phi)^k)*x/(sqrt(5)*(1 - (phi^k + (-1/phi)^k)*x + (-1)^k*x^2)), where phi is the golden ratio (A001622).

Crossrefs

Cf. similar sequences of the form Fibonacci(k*n): A000045 (k = 1), A001906 (k = 2), A014445 (k = 3), A033888 (k = 4), A102312 (k = 5), A134492 (k = 6), A134498 (k = 7), A138473 (k = 8), A138590 (k = 9), this sequence (k = 10), A167398 (k = 11), A214855 (k = 15).
Cf. A000032 (Lucas numbers), A001622 (golden ratio).

Programs

  • Mathematica
    Fibonacci[10Range[0, 14]]
    FullSimplify[Table[(((1 + Sqrt[5])/2)^(10 n) - (2/(1 + Sqrt[5]))^(10 n))/Sqrt[5], {n, 0, 12}]]
    LinearRecurrence[{123, -1}, {0, 55}, 15]
  • PARI
    a(n) = fibonacci(10*n); \\ Michel Marcus, Mar 03 2016
    
  • PARI
    concat(0, Vec(55*x/(1-123*x+x^2) + O(x^100))) \\ Altug Alkan, Mar 04 2016

Formula

G.f.: 55*x/(1 - 123*x + x^2).
a(n) = 123*a(n-1) - a(n-2).
a(n) = A000045(10*n).
Lim_{n -> infinity} a(n + 1)/a(n) = phi^10 = 122.9918693812442…

A133012 Even imperfect numbers.

Original entry on oeis.org

2, 4, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118
Offset: 1

Views

Author

Omar E. Pol, Oct 20 2007

Keywords

Crossrefs

Cf. A005843, A014445, A014494. Imperfect numbers: A132999.

A133016 Even imperfect numbers, divided by 2.

Original entry on oeis.org

1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64
Offset: 1

Views

Author

Omar E. Pol, Oct 20 2007

Keywords

Crossrefs

Cf. A005843, A014335, A014445, A014494, A026503, A028334. Imperfect numbers: A132999.

A171731 Triangle T : T(n,k)= binomial(n,k)*Fibonacci(n-k)= A007318(n,k)*A000045(n-k).

Original entry on oeis.org

0, 1, 0, 1, 2, 0, 2, 3, 3, 0, 3, 8, 6, 4, 0, 5, 15, 20, 10, 5, 0, 8, 30, 45, 40, 15, 6, 0, 13, 56, 105, 105, 70, 21, 7, 0, 21, 104, 224, 280, 210, 112, 28, 8, 0, 34, 189, 468, 672, 630, 378, 168, 36, 9, 0, 55, 340, 945, 1560, 1680, 1260, 630, 240, 45, 10, 0
Offset: 0

Views

Author

Philippe Deléham, Dec 16 2009

Keywords

Comments

Diagonal sums : A112576.
Essentially the same as A094440. - Peter Bala, Jan 06 2015

Examples

			Triangle begins :
0 ;
1,0 ;
1,2,0 ;
2,3,3,0 ;
3,8,6,4,0 ;
5,15,20,10,5,0 ;
...
		

Crossrefs

Programs

  • Mathematica
    Flatten[Table[Binomial[n,k]Fibonacci[n-k],{n,0,10},{k,0,n}]] (* Harvey P. Dale, Jan 16 2013 *)

Formula

Sum_{k, 0<=k<=n} T(n,k)*x^k = A000045(n), A001906(n), A093131(n), A099453(n-1), A081574(n), A081575(n) for x = 0,1,2,3,4,5 respectively. Sum_{k, 0<=k<=n} T(n,k)*2^(n-k) = A014445(n).
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