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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A309586 Primes p with 1 zero in a fundamental period of A006190 mod p.

Original entry on oeis.org

2, 3, 23, 43, 53, 61, 79, 101, 103, 107, 127, 131, 139, 173, 179, 191, 199, 211, 251, 263, 277, 283, 311, 347, 367, 419, 433, 439, 443, 467, 491, 503, 523, 547, 563, 569, 571, 599, 607, 647, 659, 677, 719, 727, 751, 757, 823, 829, 859, 881, 883, 887, 907
Offset: 1

Views

Author

Jianing Song, Aug 10 2019

Keywords

Comments

Primes p such that A322906(p) = 1.
For p > 2, p is in this sequence if and only if A175182(p) == 2 (mod 4), and if and only if A322907(p) == 2 (mod 4). For a proof of the equivalence between A322906(p) = 1 and A322907(p) == 2 (mod 4), see Section 2 of my link below.
This sequence contains all primes congruent to 3, 23, 27, 35, 43, 51 modulo 52. This corresponds to case (3) for k = 11 in the Conclusion of Section 1 of my link below.
Conjecturely, this sequence has density 1/3 in the primes. [Comment rewritten by Jianing Song, Jun 16 2024 and Jun 25 2024]

Crossrefs

Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = m*x(n+1) + x(n). Let w(k) be the number of zeros in a fundamental period of {x(n)} modulo k.
| m=1 | m=2 | m=3
-----------------------------+----------+---------+----------
The sequence {x(n)} | A000045 | A000129 | A006190
The sequence {w(k)} | A001176 | A214027 | A322906
Primes p such that w(p) = 1 | A112860* | A309580 | this seq
Primes p such that w(p) = 2 | A053027 | A309581 | A309587
Primes p such that w(p) = 4 | A053028 | A261580 | A309588
Numbers k such that w(k) = 1 | A053031 | A309583 | A309591
Numbers k such that w(k) = 2 | A053030 | A309584 | A309592
Numbers k such that w(k) = 4 | A053029 | A309585 | A309593
* and also A053032 U {2}

Programs

  • PARI
    forprime(p=2, 900, if(A322906(p)==1, print1(p, ", ")))

A309587 Primes p with 2 zeros in a fundamental period of A006190 mod p.

Original entry on oeis.org

7, 11, 17, 19, 31, 47, 59, 67, 71, 83, 113, 151, 163, 167, 223, 227, 239, 257, 271, 307, 313, 331, 337, 359, 379, 383, 431, 463, 479, 487, 499, 521, 587, 601, 619, 631, 641, 643, 673, 683, 691, 739, 743, 787, 809, 811, 827, 839, 863, 947, 967, 983
Offset: 1

Views

Author

Jianing Song, Aug 10 2019

Keywords

Comments

Primes p such that A322906(p) = 2.
For p > 2, p is in this sequence if and only if 8 divides A175182(p), and if and only if 4 divides A322907(p). For a proof of the equivalence between A322906(p) = 2 and 4 dividing A322907(p), see Section 2 of my link below.
This sequence contains all primes congruent to 7, 11, 15, 19, 31, 47 modulo 52. This corresponds to case (2) for k = 11 in the Conclusion of Section 1 of my link below.
Conjecturely, this sequence has density 1/3 in the primes. [Comment rewritten by Jianing Song, Jun 16 2024 and Jun 25 2024]

Crossrefs

Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = m*x(n+1) + x(n). Let w(k) be the number of zeros in a fundamental period of {x(n)} modulo k.
| m=1 | m=2 | m=3
-----------------------------+----------+---------+----------
The sequence {x(n)} | A000045 | A000129 | A006190
The sequence {w(k)} | A001176 | A214027 | A322906
Primes p such that w(p) = 1 | A112860* | A309580 | A309586
Primes p such that w(p) = 2 | A053027 | A309581 | this seq
Primes p such that w(p) = 4 | A053028 | A261580 | A309588
Numbers k such that w(k) = 1 | A053031 | A309583 | A309591
Numbers k such that w(k) = 2 | A053030 | A309584 | A309592
Numbers k such that w(k) = 4 | A053029 | A309585 | A309593
* and also A053032 U {2}

Programs

  • PARI
    forprime(p=2, 1000, if(A322906(p)==2, print1(p, ", ")))

A309588 Primes p with 4 zeros in a fundamental period of A006190 mod p.

Original entry on oeis.org

5, 13, 29, 37, 41, 73, 89, 97, 109, 137, 149, 157, 181, 193, 197, 229, 233, 241, 269, 281, 293, 317, 349, 353, 373, 389, 397, 401, 409, 421, 449, 457, 461, 509, 541, 557, 577, 593, 613, 617, 653, 661, 701, 709, 733, 761, 769, 773, 797, 821, 853, 857, 877
Offset: 1

Views

Author

Jianing Song, Aug 10 2019

Keywords

Comments

Primes p such that A322906(p) = 4.
For p > 2, p is in this sequence if and only if A175182(p) == 4 (mod 8), and if and only if A322907(p) is odd. For a proof of the equivalence between A322906(p) = 4 and A322907(p) being odd, see Section 2 of my link below.
This sequence contains all primes congruent to 5, 21, 33, 37, 41, 45 modulo 52. This corresponds to case (1) for k = 11 in the Conclusion of Section 1 of my link below.
Conjecturely, this sequence has density 1/3 in the primes. [Comment rewritten by Jianing Song, Jun 16 2024 and Jun 25 2024]

Crossrefs

Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = m*x(n+1) + x(n). Let w(k) be the number of zeros in a fundamental period of {x(n)} modulo k.
| m=1 | m=2 | m=3
-----------------------------+----------+---------+----------
The sequence {x(n)} | A000045 | A000129 | A006190
The sequence {w(k)} | A001176 | A214027 | A322906
Primes p such that w(p) = 1 | A112860* | A309580 | A309586
Primes p such that w(p) = 2 | A053027 | A309581 | A309587
Primes p such that w(p) = 4 | A053028 | A261580 | this seq
Numbers k such that w(k) = 1 | A053031 | A309583 | A309591
Numbers k such that w(k) = 2 | A053030 | A309584 | A309592
Numbers k such that w(k) = 4 | A053029 | A309585 | A309593
* and also A053032 U {2}

Programs

  • PARI
    forprime(p=2, 900, if(A322906(p)==4, print1(p, ", ")))

A309591 Numbers k with 1 zero in a fundamental period of A006190 mod k.

Original entry on oeis.org

1, 2, 3, 4, 6, 9, 12, 18, 23, 27, 36, 43, 46, 53, 54, 61, 69, 79, 81, 86, 92, 101, 103, 106, 107, 108, 122, 127, 129, 131, 138, 139, 158, 159, 162, 172, 173, 179, 183, 191, 199, 202, 206, 207, 211, 212, 214, 237, 243, 244, 251, 254, 258, 262, 263, 276
Offset: 1

Views

Author

Jianing Song, Aug 10 2019

Keywords

Comments

Numbers k such that A322906(k) = 1.
The odd numbers k satisfy A175182(k) == 2 (mod 4).

Crossrefs

Cf. A175182.
Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = m*x(n+1) + x(n). Let w(k) be the number of zeros in a fundamental period of {x(n)} modulo k.
| m=1 | m=2 | m=3
-----------------------------+----------+---------+----------
The sequence {x(n)} | A000045 | A000129 | A006190
The sequence {w(k)} | A001176 | A214027 | A322906
Primes p such that w(p) = 1 | A112860* | A309580 | A309586
Primes p such that w(p) = 2 | A053027 | A309581 | A309587
Primes p such that w(p) = 4 | A053028 | A261580 | A309588
Numbers k such that w(k) = 1 | A053031 | A309583 | this seq
Numbers k such that w(k) = 2 | A053030 | A309584 | A309592
Numbers k such that w(k) = 4 | A053029 | A309585 | A309593
* and also A053032 U {2}

Programs

  • PARI
    for(k=1, 300, if(A322906(k)==1, print1(k, ", ")))

A309592 Numbers k with 2 zeros in a fundamental period of A006190 mod k.

Original entry on oeis.org

7, 8, 11, 14, 15, 16, 17, 19, 20, 21, 22, 24, 28, 30, 31, 32, 33, 34, 35, 38, 39, 40, 42, 44, 45, 47, 48, 49, 51, 52, 55, 56, 57, 59, 60, 62, 63, 64, 66, 67, 68, 70, 71, 72, 75, 76, 77, 78, 80, 83, 84, 85, 87, 88, 90, 91, 93, 94, 95, 96, 98, 99, 100, 102, 104
Offset: 1

Views

Author

Jianing Song, Aug 10 2019

Keywords

Comments

Numbers k such that A322906(k) = 2.
This sequence contains all numbers k such that 4 divides A322907(k). As a consequence, this sequence contains all numbers congruent to 7, 11, 15, 19, 31, 47 modulo 52.
This sequence contains all odd numbers k such that 8 divides A175182(k).

Crossrefs

Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = m*x(n+1) + x(n). Let w(k) be the number of zeros in a fundamental period of {x(n)} modulo k.
| m=1 | m=2 | m=3
-----------------------------+----------+---------+----------
The sequence {x(n)} | A000045 | A000129 | A006190
The sequence {w(k)} | A001176 | A214027 | A322906
Primes p such that w(p) = 1 | A112860* | A309580 | A309586
Primes p such that w(p) = 2 | A053027 | A309581 | A309587
Primes p such that w(p) = 4 | A053028 | A261580 | A309588
Numbers k such that w(k) = 1 | A053031 | A309583 | A309591
Numbers k such that w(k) = 2 | A053030 | A309584 | this seq
Numbers k such that w(k) = 4 | A053029 | A309585 | A309593
* and also A053032 U {2}

Programs

  • PARI
    for(k=1, 100, if(A322906(k)==2, print1(k, ", ")))

A309593 Numbers k with 4 zeros in a fundamental period of A006190 mod k.

Original entry on oeis.org

5, 10, 13, 25, 26, 29, 37, 41, 50, 58, 65, 73, 74, 82, 89, 97, 109, 125, 130, 137, 145, 146, 149, 157, 169, 178, 181, 185, 193, 194, 197, 205, 218, 229, 233, 241, 250, 269, 274, 281, 290, 293, 298, 314, 317, 325, 338, 349, 353, 362, 365, 370, 373, 377
Offset: 1

Views

Author

Jianing Song, Aug 10 2019

Keywords

Comments

Numbers k such that A322906(k) = 4.
Also numbers k such that A214027(k) is odd.

Crossrefs

Cf. A322907.
Let {x(n)} be a sequence defined by x(0) = 0, x(1) = 1, x(n+2) = m*x(n+1) + x(n). Let w(k) be the number of zeros in a fundamental period of {x(n)} modulo k.
| m=1 | m=2 | m=3
-----------------------------+----------+---------+----------
The sequence {x(n)} | A000045 | A000129 | A006190
The sequence {w(k)} | A001176 | A214027 | A322906
Primes p such that w(p) = 1 | A112860* | A309580 | A309586
Primes p such that w(p) = 2 | A053027 | A309581 | A309587
Primes p such that w(p) = 4 | A053028 | A261580 | A309588
Numbers k such that w(k) = 1 | A053031 | A309583 | A309591
Numbers k such that w(k) = 2 | A053030 | A309584 | A309592
Numbers k such that w(k) = 4 | A053029 | A309585 | this seq
* and also A053032 U {2}

Programs

  • PARI
    for(k=1, 400, if(A322906(k)==4, print1(k, ", ")))

A104714 Greatest common divisor of a Fibonacci number and its index.

Original entry on oeis.org

0, 1, 1, 1, 1, 5, 2, 1, 1, 1, 5, 1, 12, 1, 1, 5, 1, 1, 2, 1, 5, 1, 1, 1, 24, 25, 1, 1, 1, 1, 10, 1, 1, 1, 1, 5, 36, 1, 1, 1, 5, 1, 2, 1, 1, 5, 1, 1, 48, 1, 25, 1, 1, 1, 2, 5, 7, 1, 1, 1, 60, 1, 1, 1, 1, 5, 2, 1, 1, 1, 5, 1, 72, 1, 1, 25, 1, 1, 2, 1, 5, 1, 1, 1, 12, 5, 1, 1, 1, 1, 10, 13, 1, 1, 1, 5, 96, 1
Offset: 0

Views

Author

Harmel Nestra (harmel.nestra(AT)ut.ee), Apr 23 2005

Keywords

Comments

Considering this sequence is a natural sequel to the investigation of the problem when F_n is divisible by n (the numbers occurring in A023172). This sequence has several nice properties. (1) n | m implies a(n) | a(m) for arbitrary naturals n and m. This property is a direct consequence of the analogous well-known property of Fibonacci numbers. (2) gcd (a(n), a(m)) = a(gcd(n, m)) for arbitrary naturals n and m. Also this property follows directly from the analogous (perhaps not so well-known) property of Fibonacci numbers. (3) a(n) * a(m) | a(n * m) for arbitrary naturals n and m. This property is remarkable especially in the light that the analogous proposition for Fibonacci numbers fails if n and m are not relatively prime (e.g. F_3 * F_3 does not divide F_9). (4) The set of numbers satisfying a(n) = n is closed w.r.t. multiplication. This follows easily from (3).

Examples

			The natural numbers:    0 1 2 3 4 5 6  7  8  9 10 11  12 ...
The Fibonacci numbers:  0 1 1 2 3 5 8 13 21 34 55 89 144 ...
The corresponding GCDs: 0 1 1 1 1 5 2  1  1  1  5  1  12 ...
		

Crossrefs

Cf. A023172, A000045, A001177, A001175, A001176. a(n) = gcd(A000045(n), A001477(n)). a(n) = n iff n occurs in A023172 iff n | A000045(n).
Cf. A074215 (a(n)==1).

Programs

  • Haskell
    let fibs@(_ : fs) = 0 : 1 : zipWith (+) fibs fs in 0 : zipWith gcd [1 ..] fs
    
  • Maple
    b:= proc(n) option remember; local r, M, p; r, M, p:=
          <<1|0>, <0|1>>, <<0|1>, <1|1>>, n;
          do if irem(p, 2, 'p')=1 then r:= r.M mod n fi;
             if p=0 then break fi; M:= M.M mod n
          od; r[1, 2]
        end:
    a:= n-> igcd(n, b(n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Apr 05 2017
  • Mathematica
    Table[GCD[Fibonacci[n],n],{n,0,97}] (* Alonso del Arte, Nov 22 2010 *)
  • PARI
    a(n)=if(n,gcd(n,lift(Mod([1,1;1,0],n)^n)[1,2]),0) \\ Charles R Greathouse IV, Sep 24 2013

Formula

a(n) = gcd(F(n), n).

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.

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

A237517 Pisano period of n^2 divided by Pisano period of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 1, 7, 8, 9, 5, 11, 1, 13, 7, 15, 16, 17, 9, 19, 10, 21, 11, 23, 4, 25, 13, 27, 7, 29, 5, 31, 32, 33, 17, 35, 9, 37, 19, 39, 40, 41, 7, 43, 44, 45, 23, 47, 16, 49, 25, 17, 26, 53, 27, 55, 14, 19, 29, 59, 5, 61, 31, 63, 64, 65, 11, 67, 34, 23
Offset: 1

Author

Keywords

Comments

For all n, a(n) | n.
Conjecture (Saha & Karthik): a(n) = 1 only for n = 1, 6, and 12.

Crossrefs

Programs

  • Mathematica
    pp[1] = 1; pp[n_] := For[k = 1, True, k++, If[Mod[Fibonacci[k], n] == 0 && Mod[Fibonacci[k+1], n] == 1, Return[k]]];
    a[n_] := pp[n^2]/pp[n];
    Array[a, 100] (* Jean-François Alcover, Dec 04 2018 *)
  • PARI
    fibmod(n,m)=((Mod([1,1;1,0],m))^n)[1,2]
    entry_p(p)=my(k=1,c=Mod(1,p),o); while(c,[o,c]=[c,c+o];k++); k
    entry(n)=if(n==1,return(1)); my(f=factor(n), v); v=vector(#f~, i, if(f[i,1]>1e14,entry_p(f[i,1]^f[i,2]), entry_p(f[i,1])*f[i,1]^(f[i,2] - 1))); if(f[1,1]==2&&f[1,2]>1, v[1]=3<
    				
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