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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A079344 F(n) mod 8, where F(n) = A000045(n) is the n-th Fibonacci number.

Original entry on oeis.org

0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5, 2, 7, 1, 0, 1, 1, 2, 3, 5, 0, 5, 5
Offset: 0

Views

Author

Jon Perry, Jan 04 2003

Keywords

Comments

This sequence does not contain the complete set of residues modulo 8. See A079002. - Michel Marcus, Jan 31 2020

Examples

			a(8) = F(8) mod 8 = 21 mod 8 = 5.
		

Crossrefs

Programs

  • Magma
    [Fibonacci(n) mod 8: n in [0..100]]; // Vincenzo Librandi, Feb 04 2014
  • Mathematica
    Mod[Fibonacci[Range[0,110]],8] (* or *) LinearRecurrence[ {1,0,0,-1,1,0,0,-1,1},{0,1,1,2,3,5,0,5,5},110] (* Harvey P. Dale, Jan 16 2014 *)
  • PARI
    for (n=0,100,print1(fibonacci(n)%8","))
    

Formula

Sequence is periodic with Pisano period 12 = A001175(8).
G.f.: -x*(1+x^2+x^3+3*x^4+6*x^6-5*x^5+x^7) / ( (x-1)*(x^2-x+1)*(1+x+x^2)*(x^4-x^2+1) ). - R. J. Mathar, Aug 08 2012

Extensions

Edited by N. J. A. Sloane, Dec 06 2008 at the suggestion of R. J. Mathar

A082117 Fibonacci sequence (mod 6).

Original entry on oeis.org

0, 1, 1, 2, 3, 5, 2, 1, 3, 4, 1, 5, 0, 5, 5, 4, 3, 1, 4, 5, 3, 2, 5, 1, 0, 1, 1, 2, 3, 5, 2, 1, 3, 4, 1, 5, 0, 5, 5, 4, 3, 1, 4, 5, 3, 2, 5, 1, 0, 1, 1, 2, 3, 5, 2, 1, 3, 4, 1, 5, 0, 5, 5, 4, 3, 1, 4, 5, 3, 2, 5, 1, 0, 1, 1, 2, 3, 5, 2, 1, 3, 4, 1, 5, 0, 5, 5, 4, 3, 1, 4, 5, 3, 2, 5, 1, 0, 1, 1, 2, 3, 5, 2
Offset: 0

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Author

Eric W. Weisstein, Apr 03 2003

Keywords

Crossrefs

Programs

Formula

Sequence is periodic with Pisano period 24 = A001175(6).
G.f.: -x*(x^22 + 5*x^21 + 2*x^20 + 3*x^19 + 5*x^18 + 4*x^17 + x^16 + 3*x^15 + 4*x^14 + 5*x^13 + 5*x^12 + 5*x^10 + x^9 + 4*x^8 + 3*x^7 + x^6 + 2*x^5 + 5*x^4 + 3*x^3 + 2*x^2 + x + 1)/((x - 1)*(x + 1)*(x^2 - x + 1)*(x^2 + 1)*(x^2 + x + 1)*(x^4 - x^2 + 1)*(x^4 + 1)*(x^8 - x^4 + 1)). - Colin Barker, Aug 15 2012

Extensions

Added a(0)=0 from Vincenzo Librandi, Feb 04 2014

A322907 Entry points for the 3-Fibonacci numbers A006190.

Original entry on oeis.org

1, 3, 2, 6, 3, 6, 8, 6, 6, 3, 4, 6, 13, 24, 6, 12, 8, 6, 20, 6, 8, 12, 22, 6, 15, 39, 18, 24, 7, 6, 32, 24, 4, 24, 24, 6, 19, 60, 26, 6, 7, 24, 42, 12, 6, 66, 48, 12, 56, 15, 8, 78, 26, 18, 12, 24, 20, 21, 12, 6, 30, 96, 24, 48, 39, 12, 68, 24, 22, 24, 72, 6
Offset: 1

Views

Author

Jianing Song, Jan 05 2019

Keywords

Comments

a(n) is the smallest k > 0 such that n divides A006190(k).
a(n) is also called the rank of A006190(n) modulo n.
For primes p == 1, 9, 17, 25, 29, 49 (mod 52), a(p) divides (p - 1)/2.
For primes p == 3, 23, 27, 35, 43, 51 (mod 52), a(p) divides p - 1, but a(p) does not divide (p - 1)/2.
For primes p == 5, 21, 33, 37, 41, 45 (mod 52), a(p) divides (p + 1)/2.
For primes p == 7, 11, 15, 19, 31, 47 (mod 52), a(p) divides p + 1, but a(p) does not divide (p + 1)/2.
a(n) <= (12/7)*n for all n, where the equality holds if and only if n = 2*7^e, e >= 1.

Crossrefs

Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = k*x(n+1) + x(n). Then the periods, ranks and the ratios of the periods to the ranks modulo a given integer n are given by:
k = 1: A001175 (periods), A001177 (ranks), A001176 (ratios).
k = 2: A175181 (periods), A214028 (ranks), A214027 (ratios).
k = 3: A175182 (periods), this sequence (ranks), A322906 (ratios).
Cf. A006190.

Programs

  • PARI
    A006190(m) = ([3, 1; 1, 0]^m)[2, 1]
    a(n) = my(i=1); while(A006190(i)%n!=0, i++); i

Formula

a(m*n) = a(m)*a(n) if gcd(m, n) = 1.
For odd primes p, a(p^e) = p^(e-1)*a(p) if p^2 does not divide a(p). Any counterexample would be a 3-Wall-Sun-Sun prime.
a(2^e) = 3 if e = 1, 6 if e = 2 and 3*2^(e-2) if e >= 3. a(13^e) = 13^e, e >= 1.

A020695 Pisot sequence E(2,3).

Original entry on oeis.org

2, 3, 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

Views

Author

Keywords

Comments

Pisano period lengths: A001175. - R. J. Mathar, Aug 10 2012

Crossrefs

Subsequence of A000045. See A008776 for definitions of Pisot sequences.
See A000045 for the Fibonacci numbers.

Programs

Formula

a(n) = Fibonacci(n+3); a(n) = a(n-1) + a(n-2).
G.f.: (2+x)/(1-x-x^2). - Philippe Deléham, Nov 19 2008
a(n) = (2^(-n)*((1-sqrt(5))^n*(-2+sqrt(5))+(1+sqrt(5))^n*(2+sqrt(5))))/sqrt(5). - Colin Barker, Jun 05 2016
E.g.f.: 2*(2*sqrt(5)*sinh(sqrt(5)*x/2) + 5*cosh(sqrt(5)*x/2))*exp(x/2)/5. - Ilya Gutkovskiy, Jun 05 2016

A022130 Fibonacci sequence beginning 4,9.

Original entry on oeis.org

4, 9, 13, 22, 35, 57, 92, 149, 241, 390, 631, 1021, 1652, 2673, 4325, 6998, 11323, 18321, 29644, 47965, 77609, 125574, 203183, 328757, 531940, 860697, 1392637, 2253334, 3645971, 5899305, 9545276, 15444581, 24989857, 40434438, 65424295, 105858733, 171283028
Offset: 0

Views

Author

Keywords

Comments

The associated Pisano series starts as in A001175, but differs for example for modulus 29 where it is 7, not 14. - R. J. Mathar, Nov 02 2011
The Pisano period also differs for modulus 58, where it is 21 instead of 42. Otherwise, the Pisano periods coincide with those of the Fibonacci numbers. - Klaus Purath, Jun 26 2022

Crossrefs

Programs

  • Magma
    a0:=4; a1:=9; [GeneralizedFibonacciNumber(a0, a1, n): n in [0..35]]; // Vincenzo Librandi, Jan 25 2017
  • Maple
    a:= n-> (<<0|1>, <1|1>>^n.<<4, 9>>)[1,1]:
    seq(a(n), n=0..40);  # Alois P. Heinz, Feb 22 2017
  • Mathematica
    a={};b=4;c=9;AppendTo[a,b];AppendTo[a,c];Do[b=b+c;AppendTo[a,b];c=b+c;AppendTo[a,c],{n,1,40,1}];a (* Vladimir Joseph Stephan Orlovsky, Jul 23 2008 *)
    LinearRecurrence[{1,1},{4,9},40] (* Harvey P. Dale, Dec 15 2011 *)
  • PARI
    a(n)=4*fibonacci(n-1)+9*fibonacci(n) \\ Charles R Greathouse IV, Jun 05 2011
    

Formula

a(n) = 4*Fibonacci(n+2) + Fibonacci(n).
G.f.: (4 + 5*x)/(1-x-x^2). - Philippe Deléham, Nov 19 2008
a(n)= Fibonacci(n-2) + Fibonacci(n+5). - Gary Detlefs, Mar 31 2012

A079002 Numbers n such that the Fibonacci residues F(k) mod n form the complete set (0,1,2,...,n-1).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 9, 10, 14, 15, 20, 25, 27, 30, 35, 45, 50, 70, 75, 81, 100, 125, 135, 150, 175, 225, 243, 250, 350, 375, 405, 500, 625, 675, 729, 750, 875, 1125, 1215, 1250, 1750, 1875, 2025, 2187, 2500, 3125, 3375, 3645, 3750, 4375, 5625, 6075, 6250, 6561
Offset: 1

Views

Author

Benoit Cloitre, Feb 01 2003

Keywords

Examples

			Fibonacci numbers (A000045) are 0,1,1,2,3,5,8,... and their residues mod 5 are 0,1,1,2,3,0,3,3,4,...; i.e., all possible remainders mod 5 occur in the Fibonacci sequence mod 5, so 5 is in the sequence. This is not true for n=8, so 8 is not in the sequence.
		

References

  • R. L. Graham, D. E. Knuth and O. Patashnick, "Concrete Mathematics", second edition, Addison Wesley, 1994, ex. 6.85, p. 318, p. 562.

Crossrefs

Programs

Formula

Consists of the integers of the forms 5^k, 2*5^k, 4*5^k, 3^j*5^k, 6*5^k, 7*5^k and 14*5^k [see Concrete Mathematics].

Extensions

Corrected by Ron Knott, Jan 05 2005
Entry revised by N. J. A. Sloane, Nov 28 2006, following a suggestion from Martin Fuller

A128924 T(n,m) is the number of m's in the fundamental period of Fibonacci numbers mod n.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Apr 25 2007

Keywords

Comments

T(n,m) is the triangle read by rows, 0<=m
A118965 and A066853 give numbers of zeros and nonzeros in n-th row, respectively. - Reinhard Zumkeller, Jan 16 2014

Examples

			{F(k) mod 4} has fundamental period (0,1,1,2,3,1), see A079343, with
T(4,0)=1 zero, T(4,1)=3 ones, T(4,2)=1 two's, T(4,3)=1 three's. The triangle starts
1,
1, 2,
2, 3, 3,
1, 3, 1, 1,
4, 4, 4, 4, 4,
2, 6, 3, 4, 3, 6,
2, 4, 2, 1, 1, 2, 4,
2, 3, 2, 1, 0, 3, 0, 1,
2, 5, 2, 2, 2, 2, 2, 2, 5,
4, 8, 4, 8, 4, 8, 4, 8, 4, 8,
1, 3, 2, 1, 0, 1, 0, 0, 1, 0, 1,
2, 5, 2, 2, 1, 5, 0, 1, 1, 2, 2, 1,
4, 4, 2, 2, 0, 4, 0, 0, 4, 0, 2, 2, 4,
2, 8, 2, 2, 1, 4, 4, 4, 4, 4, 1, 2, 2, 8,
2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3,
2, 3, 4, 1, 0, 3, 0, 1, 2, 3, 0, 1, 0, 3, 0, 1,
4, 4, 2, 2, 4, 2, 0, 0, 2, 2, 0, 0, 2, 4, 2, 2, 4,
		

Crossrefs

Cf. A053029, A053030, A053031, A001175 (row sums), A001176 (1st column).

Programs

  • Haskell
    import Data.List (group, sort)
    a128924 n k = a128924_tabl !! (n-1) !! (k-1)
    a128924_tabl = map a128924_row [1..]
    a128924_row 1 = [1]
    a128924_row n = f [0..n-1] $ group $ sort $ g 1 ps where
       f []     _                            = []
       f (v:vs) wss'@(ws:wss) | head ws == v = length ws : f vs wss
                              | otherwise    = 0 : f vs wss'
       g 0 (1 : xs) = []
       g _ (x : xs) = x : g x xs
       ps = 1 : 1 : zipWith (\u v -> (u + v) `mod` n) (tail ps) ps
    -- Reinhard Zumkeller, Jan 16 2014
  • Maple
    A128924 := proc(m,h)
        local resul,k,M ;
        resul :=0 ;
        for k from 0 to A001175(m)-1 do
            M := combinat[fibonacci](k) mod m ;
            if M = h then
                resul := resul+1 ;
            end if ;
        end do;
        resul ;
    end proc:
    seq(seq(A128924(m,h),h=0..m-1),m=1..17) ;
  • Mathematica
    A001175[1] = 1; A001175[n_] := For[k = 1, True, k++, If[Mod[Fibonacci[k], n] == 0 && Mod[Fibonacci[k+1], n] == 1, Return[k]]]; T[m_, h_] := Module[{resul, k, M}, resul = 0; For[k = 0, k <= A001175[m]-1, k++, M = Mod[Fibonacci[k], m]; If[ M == h, resul++]]; Return[resul]]; Table[T[m, h], {m, 1, 17}, {h, 0, m-1}] // Flatten (* Jean-François Alcover, Feb 11 2015, after Maple code *)

Formula

T(n,n) = A235715(n). - Reinhard Zumkeller, Jan 17 2014

A175183 Pisano period of the 4-Fibonacci numbers A001076.

Original entry on oeis.org

1, 2, 8, 2, 20, 8, 16, 4, 8, 20, 10, 8, 28, 16, 40, 8, 12, 8, 6, 20, 16, 10, 16, 8, 100, 28, 24, 16, 14, 40, 10, 16, 40, 12, 80, 8, 76, 6, 56, 20, 40, 16, 88, 10, 40, 16, 32, 8, 112, 100, 24, 28, 36, 24, 20, 16, 24, 14, 58, 40, 20, 10, 16, 32, 140, 40, 136, 12, 16, 80, 70, 8, 148, 76
Offset: 1

Author

R. J. Mathar, Mar 01 2010

Keywords

Comments

Period of the sequence defined by reading A001076 modulo n.

Programs

  • Maple
    F := proc(k,n) option remember; if n <= 1 then n; else k*procname(k,n-1)+procname(k,n-2) ; end if; end proc:
    Pper := proc(k,m) local cha, zer,n,fmodm ; cha := [] ; zer := [] ; for n from 0 do fmodm := F(k,n) mod m ; cha := [op(cha),fmodm] ; if fmodm = 0 then zer := [op(zer),n] ; end if; if nops(zer) = 5 then break; end if; end do ; if [op(1..zer[2],cha) ] = [ op(zer[2]+1..zer[3],cha) ] and [op(1..zer[2],cha)] = [ op(zer[3]+1..zer[4],cha) ] and [op(1..zer[2],cha)] = [ op(zer[4]+1..zer[5],cha) ] then return zer[2] ; elif [op(1..zer[3],cha) ] = [ op(zer[3]+1..zer[5],cha) ] then return zer[3] ; else return zer[5] ; end if; end proc:
    k := 4 ; seq( Pper(k,m),m=1..80) ;
  • Mathematica
    Table[s = t = Mod[{0, 1}, n]; cnt=1; While[tmp = Mod[4*t[[2]] + t[[1]], n]; t[[1]] = t[[2]]; t[[2]] = tmp; s!= t, cnt++]; cnt, {n, 100}] (* Vincenzo Librandi, Dec 20 2012, after T. D. Noe *)

A175184 Pisano period of the 5-Fibonacci numbers, A052918 preceded by 0.

Original entry on oeis.org

1, 3, 8, 6, 2, 24, 6, 12, 8, 6, 24, 24, 12, 6, 8, 24, 36, 24, 40, 6, 24, 24, 22, 24, 10, 12, 8, 6, 116, 24, 64, 48, 24, 36, 6, 24, 76, 120, 24, 12, 28, 24, 88, 24, 8, 66, 96, 24, 42, 30, 72, 12, 52, 24, 24, 12, 40, 348, 58, 24, 124, 192, 24, 96, 12, 24, 66, 36, 88, 6, 70, 24, 148
Offset: 1

Author

R. J. Mathar, Mar 01 2010

Keywords

Comments

Period of the sequence defined by reading A052918 modulo n.

Programs

  • Maple
    F := proc(k,n) option remember; if n <= 1 then n; else k*procname(k,n-1)+procname(k,n-2) ; end if; end proc:
    Pper := proc(k,m) local cha, zer,n,fmodm ; cha := [] ; zer := [] ; for n from 0 do fmodm := F(k,n) mod m ; cha := [op(cha),fmodm] ; if fmodm = 0 then zer := [op(zer),n] ; end if; if nops(zer) = 5 then break; end if; end do ; if [op(1..zer[2],cha) ] = [ op(zer[2]+1..zer[3],cha) ] and [op(1..zer[2],cha)] = [ op(zer[3]+1..zer[4],cha) ] and [op(1..zer[2],cha)] = [ op(zer[4]+1..zer[5],cha) ] then return zer[2] ; elif [op(1..zer[3],cha) ] = [ op(zer[3]+1..zer[5],cha) ] then return zer[3] ; else return zer[5] ; end if; end proc:
    k := 5 ; seq( Pper(k,m),m=1..80) ;
  • Mathematica
    Table[s = t = Mod[{0, 1}, n]; cnt = 1; While[tmp = Mod[5*t[[2]] + t[[1]], n]; t[[1]] = t[[2]]; t[[2]] = tmp; s!= t, cnt++]; cnt, {n, 100}] (* Vincenzo Librandi, Dec 20 2012, after T. D. Noe *)

A233285 a(n) = largest m such that m! divides n-th Fibonacci number; a(n) = A055881(A000045(n)).

Original entry on oeis.org

1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 6, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 7
Offset: 1

Author

Antti Karttunen, Dec 06 2013

Keywords

Comments

The lengths of palindromic prefixes begin as:
1, 2, 5, 8, 11, 23, 35, 47, 59, 119, 239, 359, 479, 959, 1439, 1919, ...
+1 results: 2, 3, 6, 9, 12, 24, 36, 48, 60, 120, 240, 360, 480, 960, 1440, 1920, ...

Crossrefs

Differs from A233284 for the first time at n=120, where a(120)=7, while A233284(120)=12.
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