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 1-8 of 8 results.

A093062 a(n) = Fibonacci(prime(n)) - prime(Fibonacci(n)).

Original entry on oeis.org

-1, 0, 2, 8, 78, 214, 1556, 4108, 28518, 513972, 1345808, 24156990, 165578670, 433491846, 2971210580, 53316283380, 956722012572, 2504730758802, 44945570173074, 308061521102198, 806515532933562, 14472334024479534, 99194853094422264, 1779979416004150202
Offset: 1

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Author

Dennis S. Kluk (mathemagician(AT)ameritech.net), May 08 2004

Keywords

Comments

Composition of prime( ) and Fibonacci( ) is not commutative. Does a prime p ever divide Fibonacci(prime(p)) - prime(Fibonacci(p))?
Note that a(3) = 2 is the only prime element of the sequence. This is because after 2, all primes are odd; and the Fibonacci number F(n) is even only for n = 3k for some integer k [which relates to the fact that A082115 Fibonacci sequence (mod 3) is periodic with Pisano period 8]. Hence after a(1) = -1, Fibonacci(prime(n)) - prime(Fibonacci(n)) is always the difference of two odd numbers, hence is even. - Jonathan Vos Post, Jan 23 2006
Is a(i) ever divisible by i? Answer: yes. The quotient is an integer for i = 4, 28 and 30 through 63. - Dennis S. Kluk (mathemagician(AT)ameritech.net), Aug 16 2006

Examples

			a(11) = Fibonacci(prime(11)) - prime(Fibonacci(11)) = 1345808.
		

Crossrefs

Programs

  • Magma
    [Fibonacci(NthPrime(n)) - NthPrime(Fibonacci(n)): n in [1..30]]; // Vincenzo Librandi, Apr 10 2020
  • Mathematica
    For[i=1, i<61, i++, Print[i, " ", Fibonacci[Prime[i]]-Prime[Fibonacci[i]]]]
    Table[Fibonacci[Prime[n]]-Prime[Fibonacci[n]],{n,30}] (* Harvey P. Dale, Jul 02 2018 *)
  • PARI
    a(n) = { fibonacci(prime(n)) - prime(fibonacci(n)) } \\ Harry J. Smith, Jun 20 2009
    

Formula

a(n) = Fibonacci(prime(n)) - prime(Fibonacci(n)).

A094894 a(n) = prime(Lucas(n)), Lucas numbers beginning at 2 (A000032).

Original entry on oeis.org

3, 2, 5, 7, 17, 31, 61, 109, 211, 383, 677, 1217, 2137, 3733, 6521, 11279, 19463, 33347, 56963, 97159, 165443, 280549, 474809, 801611, 1351841, 2273989, 3821689, 6412541, 10742339, 17974841, 30045019, 50163697, 83669419, 139420003, 232106309, 386086573, 641716373
Offset: 0

Views

Author

N. J. A. Sloane, Jun 15 2004

Keywords

Crossrefs

Programs

  • Magma
    [NthPrime(Lucas(n)): n in [0..40]]; // Vincenzo Librandi, Jan 14 2016
  • Mathematica
    Table[ Prime[ Fibonacci[n + 1] + Fibonacci[n - 1]], {n, 0, 35}] (* Robert G. Wilson v, Jun 16 2004 *)
    Table[Prime[LucasL[n]], {n, 0, 40}] (* Vincenzo Librandi, Jan 14 2016 *)

Formula

a(n) = prime(L(n)) = A000040(A000032(n)) = prime(Fib(n + 1) + Fib(n-1)), where Fib are the Fibonacci numbers(A000045) with Fib(-1) = -1.

Extensions

More terms from Robert G. Wilson v, Jun 16 2004
a(34)-a(36) from Vincenzo Librandi, Jan 14 2016

A181058 a(n) = prime(Fibonacci(phi(n))), where prime = A000040, Fibonacci = A000045 and phi = A000010.

Original entry on oeis.org

2, 2, 2, 2, 5, 2, 19, 5, 19, 5, 257, 5, 827, 19, 73, 73, 7793, 19, 23159, 73, 827, 257, 196687, 73, 67931, 827, 23159, 827, 4528949, 73, 12717703, 7793, 67931, 7793, 563987, 827, 274253209, 23159, 563987, 7793, 2088145739, 827, 5738374519, 67931
Offset: 1

Views

Author

Carmine Suriano, Oct 01 2010

Keywords

Comments

Phi is Euler's totient function A000010.

Examples

			a(7) = 19 since prime(fib(phi(7))) = prime(fib(6)) = prime(8) = 19 that is the 8th prime.
		

Crossrefs

Programs

Formula

a(n) = A000040(A065451(n)) = A030427(A000010(n)). - Antti Karttunen, Dec 06 2017

Extensions

More terms from Robert G. Wilson v, Oct 02 2010

A343256 Difference between prime(Fibonacci(n+1)) and prime(Fibonacci(n)).

Original entry on oeis.org

0, 1, 2, 6, 8, 22, 32, 66, 118, 204, 366, 644, 1120, 1902, 3300, 5676, 9690, 16620, 28152, 47900, 80856, 136546, 230754, 387570, 651932, 1093174, 1832286, 3065822, 5122932, 8557788, 14272702, 23779968, 39592890, 65860910, 109471248, 181821502, 301795112
Offset: 1

Views

Author

Paolo Xausa, Apr 09 2021

Keywords

Crossrefs

Cf. A000040 (primes), A000045 (Fibonacci), A030427.

Programs

Formula

a(n) = prime(Fibonacci(n+1)) - prime(Fibonacci(n)).
a(n) = A030427(n+1) - A030427(n).

A093309 a(n) = prime(prime(Fibonacci(n))).

Original entry on oeis.org

3, 3, 5, 11, 31, 67, 179, 367, 797, 1621, 3259, 6353, 12301, 23209, 42979, 79559, 145547, 264091, 476981, 854353, 1523569, 2700559, 4765693, 8385679, 14683231, 25641599, 44620633, 77443423, 134053991, 231443561, 398799287, 685660127
Offset: 1

Views

Author

Cino Hilliard, Apr 25 2004

Keywords

Crossrefs

Programs

  • Magma
    [NthPrime(NthPrime(Fibonacci(n))): n in [1..32]]; // Vincenzo Librandi, Dec 20 2015
  • Mathematica
    Table[Prime[Prime[Fibonacci[n]]], {n, 1, 20}] (* G. C. Greubel, Dec 20 2015 *)
  • PARI
    a(n) = prime(prime(fibonacci(n)))
    

Formula

a(n) = A000040(A030427(n)). - R. J. Mathar, Feb 06 2010

Extensions

More terms from Harry J. Smith, Jun 20 2009

A113842 a(n) = Prime(tribonacci(n)).

Original entry on oeis.org

2, 2, 3, 7, 17, 41, 89, 193, 419, 859, 1759, 3607, 7247, 14551, 28793, 56893, 111863, 218839, 426583, 827851, 1603769, 3097121, 5966629, 11470489, 22004617, 42142883, 80570929, 153802489, 293176621, 558130051, 1061238359, 2015569583
Offset: 2

Views

Author

Jonathan Vos Post, Jan 23 2006

Keywords

Comments

This is to the tribonacci sequence what A030427 is to the Fibonacci sequence.

Examples

			a(2) = prime(tribonacci(2)) = prime(1) = 2.
a(3) = prime(tribonacci(3)) = prime(1) = 2.
a(4) = prime(tribonacci(4)) = prime(2) = 3.
a(5) = prime(tribonacci(5)) = prime(4) = 7.
a(6) = prime(tribonacci(6)) = prime(7) = 17.
		

Crossrefs

Formula

a(n) = A000040(A000073(n)).

A117517 Numbers k such that F(2*k + 1) is prime where F(m) is a Fibonacci number.

Original entry on oeis.org

1, 2, 3, 5, 6, 8, 11, 14, 21, 23, 41, 65, 68, 179, 215, 216, 224, 254, 284, 285, 1485, 2361, 2693, 4655, 4838, 7215, 12780, 15378, 17999, 18755, 25416, 40919, 52455, 65010, 74045, 100553, 198689, 216890, 295020, 296844, 302355, 465758, 524948, 642803, 818003, 901529, 984360, 1452176
Offset: 1

Views

Author

Parthasarathy Nambi, Apr 26 2006

Keywords

Comments

For F(k) to be prime, with k > 4, it is necessary but not sufficient for k to be prime. Hence after F(4) = 3, every prime F(m) is of the form F(2*k+1) for some k. Every prime divides some Fibonacci number. See also comment to A093062. - Jonathan Vos Post, Apr 29 2006

Examples

			If k=68 then F(2*k + 1) = 19134702400093278081449423917, a prime, so 68 is a term.
		

Crossrefs

Programs

  • Magma
    [n: n in [0..1000] | IsPrime(Fibonacci(2*n+1))]; // Vincenzo Librandi, May 24 2016
  • Mathematica
    Select[Range[0, 5000], PrimeQ[Fibonacci[2 # + 1]] &] (* Vincenzo Librandi, May 24 2016 *)

Formula

a(n) = (A083668(n)-1)/2. - R. J. Mathar, Jul 08 2009
a(n) = (A001605(n+1)-1)/2, n > 1. - Vincenzo Librandi, May 24 2016

Extensions

More terms from Vincenzo Librandi, May 24 2016

A280105 a(n) = prime(Fibonacci(n)) written in base 2.

Original entry on oeis.org

10, 10, 11, 101, 1011, 10011, 101001, 1001001, 10001011, 100000001, 111001101, 1100111011, 10110111111, 101000011111, 1000110001101, 1111001110001, 11010010011101, 101101001110111, 1001101101100011, 10000100101011011, 11100010001110111, 110000000001001111
Offset: 1

Views

Author

Vincenzo Librandi, Dec 27 2016

Keywords

Crossrefs

Programs

  • Magma
    [Seqint(Intseq(NthPrime(Fibonacci(n)), 2)): n in [1..25]];
  • Mathematica
    Table[FromDigits[IntegerDigits[Prime[Fibonacci[n]], 2]], {n, 1, 30}]
Showing 1-8 of 8 results.