A163777 -id:A163777 - cp's OEIS frontend

A071642 Numbers n such that x^n + x^(n-1) + x^(n-2) + ... + x + 1 is irreducible over GF(2).

0, 1, 2, 4, 10, 12, 18, 28, 36, 52, 58, 60, 66, 82, 100, 106, 130, 138, 148, 162, 172, 178, 180, 196, 210, 226, 268, 292, 316, 346, 348, 372, 378, 388, 418, 420, 442, 460, 466, 490, 508, 522, 540, 546, 556, 562, 586, 612, 618, 652, 658, 660, 676, 700, 708, 756, 772

Offset: 1

N. J. A. Sloane, Jun 22 2002

All such polynomials of odd degree > 1 are reducible over GF(2).
For n >= 2, a(n) = A001122(n-2) - 1 due to the relationship between cycles and irreducibility. - T. D. Noe, Sep 09 2003
n such that a type-1 optimal normal basis of GF(2^n) (over GF(2)) exists. The corresponding field polynomial is the all-ones polynomial x^n+x^(n-1)+...+1. - Joerg Arndt, Feb 25 2008
From Peter R. J. Asveld, Aug 13 2009: (Start)
a(n) is also the n-th S-prime (Shuffle prime)
For N>=2, the family of shuffle permutations is defined by
p(m,N) = 2m (mod N+1) if N is even,
p(m,N) = 2m (mod N) if N is odd and 1<=mp(N,N) = N if N is odd.
N is S-prime if p(m,N) consists of a single cycle of length N.
So all S-primes are even.
N is S-prime iff p=N+1 is an odd prime number and +2 generates Z_p^* (the multiplicative group of Z_p).
a(n)/2 results in the Josephus_2-primes (A163782). Considered as sets a(n)/2 is the union of A163777 and A163779. If b(n) denotes the dual shuffle primes (A163776), then the union of a(n)/2 and b(n)/2 is equal to the Twist-primes or Queneau numbers (A054639); their intersection is equal to the Archimedes_0-primes (A163777). (End)
Conjecture: Terms >= 2 are numbers n such that P^n + P^(n-1) + P^(n-2) + ... + P + 1 is irreducible over GF(2), where P=x^2+x+1. - Luis H. Gallardo, Dec 23 2019

			For n=4 and n=6 we obtain the permutations (1 2 4 3) and (1 2 4)(3 6 5): 4 is S-prime, but 6 is not. [_Peter R. J. Asveld_, Aug 13 2009]

P. R. J. Asveld, Table of n, a(n) for n = 1..3605
Joerg Arndt, Matters Computational (The Fxtbook), section 42.9 "Gaussian normal bases", pp.914-920
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers, (2011), TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some Families of Permutations and Their Primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014.
Hélianthe Caure, Canons rythmiques et pavages modulaires, Thesis Université Pierre et Marie Curie - Paris VI, 2016. See page 108. In French.
H. Caure, C. Agon, and M. Andreatta, Modulus p Rhythmic Tiling Canons and some implementations in Open Music visual programming language, in Proceedings ICMC|SMC|2014 14-20 September 2014, Athens, Greece.
M. Olofsson, VLSI Aspects on Inversion in Finite Fields, Dissertation No. 731, Dept. Elect. Engin., Linkoping, Sweden, 2002.
Eric Weisstein's World of Mathematics, Irreducible Polynomial
Index entries for sequences related to the Josephus Problem

Cf. A001122 (primes with primitive root 2).

Join[{0, 1}, Reap[For[p = 2, p < 10^3, p = NextPrime[p], If[ MultiplicativeOrder[2, p] == p-1, Sow[p-1]]]][[2, 1]]] (* Jean-François Alcover, Dec 10 2015, adapted from PARI *)

forprime(p=3,1000,if(znorder(Mod(2,p))==p-1,print1(p-1,", "))) /* Joerg Arndt, Jul 05 2011 */

Extended by Robert G. Wilson v, Jun 24 2002

Initial terms of b-file corrected by N. J. A. Sloane, Aug 31 2009

A054639 Queneau numbers: numbers n such that the Queneau-Daniel permutation {1, 2, 3, ..., n} -> {n, 1, n-1, 2, n-2, 3, ...} is of order n.

Original entry on oeis.org

1, 2, 3, 5, 6, 9, 11, 14, 18, 23, 26, 29, 30, 33, 35, 39, 41, 50, 51, 53, 65, 69, 74, 81, 83, 86, 89, 90, 95, 98, 99, 105, 113, 119, 131, 134, 135, 146, 155, 158, 173, 174, 179, 183, 186, 189, 191, 194, 209, 210, 221, 230, 231, 233, 239

Offset: 1

Gilles Esposito-Farese (gef(AT)cpt.univ-mrs.fr), May 17 2000

nonn

The troubadour Arnaut Daniel composed sestinas based on the permutation 123456 -> 615243, which cycles after 6 iterations.
Roubaud quotes the number 141, but the corresponding Queneau-Daniel permutation is only of order 47 = 141/3.
This appears to coincide with the numbers n such that a type-2 optimal normal basis exists for GF(2^n) over GF(2). But are these two sequences really the same? - Joerg Arndt, Feb 11 2008
The answer is Yes - see Theorem 2 of the Dumas reference. [Jean-Guillaume Dumas (Jean-Guillaume.Dumas(AT)imag.fr), Mar 20 2008]
From Peter R. J. Asveld, Aug 17 2009: (Start)
a(n) is the n-th T-prime (Twist prime). For N >= 2, the family of twist permutations is defined by
p(m,N) == +2m (mod 2N+1) if 1 <= m < k = ceiling((N+1)/2),
p(m,N) == -2m (mod 2N+1) if k <= m < N.
N is T-prime if p(m,N) consists of a single cycle of length N.
The twist permutation is the inverse of the Queneau-Daniel permutation.
N is T-prime iff p=2N+1 is a prime number and exactly one of the following three conditions holds;
(1) N == 1 (mod 4) and +2 generates Z_p^* (the multiplicative group of Z_p) but -2 does not,
(2) N == 2 (mod 4) and both +2 and -2 generate Z_p^*,
(3) N == 3 (mod 4) and -2 generate Z_p^* but +2 does not. (End)
The sequence name says the permutation is of order n, but P. R. J. Asveld's comment says it's an n-cycle. Is there a proof that those conditions are equivalent for the Queneau-Daniel permutation? (They are not equivalent for any arbitrary permutation; e.g., (123)(45)(6) has order 6 but isn't a 6-cycle.) More generally, I have found that for all n <= 9450, (order of Queneau-Daniel permutation) = (length of orbit of 1) = A003558(n). Does this hold for all n? - David Wasserman, Aug 30 2011

			For N=6 and N=7 we obtain the permutations (1 2 4 5 3 6) and (1 2 4 7)(3 6)(5): 6 is T-prime, but 7 is not. - _Peter R. J. Asveld_, Aug 17 2009

Raymond Queneau, Note complémentaire sur la Sextaine, Subsidia Pataphysica 1 (1963), pp. 79-80.
Jacques Roubaud, Bibliothèque Oulipienne No 65 (1992) and 66 (1993).

P. R. J. Asveld, Table of n, a(n) for n = 1..10085
Jean-Paul Allouche, Manon Stipulanti, and Jia-Yan Yao, Doubling modulo odd integers, generalizations, and unexpected occurrences, arXiv:2504.17564 [math.NT], 2025.
Joerg Arndt, Matters Computational (The Fxtbook), section 42.9 "Gaussian normal bases", pp. 914-920
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers, TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some families of permutations and their primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Queneau Numbers--Recent Results and a Bibliography, University of Twente, 2013.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014.
Michèle Audin, Poésie, Spirales, et Battements de Cartes, Images des Mathématiques, CNRS, 2019 (in French).
M. Bringer, Sur un problème de R. Queneau, Math. Sci. Humaines No. 25 (1969) 13-20.
Jean-Guillaume Dumas, Caractérisation des Quenines et leur représentation spirale, Mathématiques et Sciences Humaines, Centre de Mathématique Sociale et de statistique, EPHE, 2008, 184 (4), pp. 9-23, hal-00188240.
G. Esposito-Farese, C program
Index entries for sequences related to the Josephus Problem

Not to be confused with Queneau's "s-additive sequences", see A003044.
A005384 is a subsequence.
Union of A163782 (Josephus_2-primes) and A163781 (dual Josephus_2-primes); also the union of A163777 (Archimedes_0-primes) and A163778 (Archimedes_1-primes); also the union of A071642/2 (shuffle primes) and A163776/2 (dual shuffle primes). - Peter R. J. Asveld, Aug 17 2009
Cf. A216371, A003558 (for which a(n) == n).

QD:= proc(n) local i;
  if n::even then map(op,[seq([n-i,i+1],i=0..n/2-1)])
  else map(op, [seq([n-i,i+1],i=0..(n-1)/2-1),[(n+1)/2]])
  fi
end proc:
select(n -> GroupTheory:-PermOrder(Perm(QD(n)))=n, [$1..1000]); # Robert Israel, May 01 2016

a[p_] := Sum[Cos[2^n Pi/((2 p + 1) )], {n, 1, p}];
Select[Range[500],Reduce[a[#] == -1/2, Rationals] &] (* Gerry Martens, May 01 2016 *)

is(n)=
{
    if (n==1, return(1));
    my( m=n%4 );
    if ( m==4, return(0) );
    my(p=2*n+1, r=znorder(Mod(2,p)));
    if ( !isprime(p), return(0) );
    if ( m==3 && r==n, return(1) );
    if ( r==2*n, return(1) ); \\ r == 1 or 2
    return(0);
}
for(n=1,10^3, if(is(n),print1(n,", ")) );
\\ Joerg Arndt, May 02 2016

a(n) = (A216371(n)-1)/2. - L. Edson Jeffery, Dec 18 2012

a(n) >> n log n, and on the Bateman-Horn-Stemmler conjecture a(n) << n log^2 n. I imagine a(n) ≍ n log n, and numerics suggest that perhaps a(n) ~ kn log n for some constant k (which seems to be around 1.122). - Charles R Greathouse IV, Aug 02 2023

A163778 Odd terms in A054639.

Original entry on oeis.org

3, 5, 9, 11, 23, 29, 33, 35, 39, 41, 51, 53, 65, 69, 81, 83, 89, 95, 99, 105, 113, 119, 131, 135, 155, 173, 179, 183, 189, 191, 209, 221, 231, 233, 239, 243, 245, 251, 261, 273, 281, 293, 299, 303, 309, 323, 329, 359, 371, 375, 393, 411, 413, 419, 429

Offset: 1

Peter R. J. Asveld, Aug 11 2009

nonn

Previous name was: The A_1-primes (Archimedes_1 primes).
We have: (1) N is an A_1-prime iff N is odd, p=2N+1 is a prime number and only one of +2 and -2 generates Z_p^* (the multiplicative group of Z_p); (2) N is an A_1-prime iff p=2N+1 is a prime number and exactly one of the following holds: (a) N == 1 (mod 4) and +2 generates Z_p^* but -2 does not, (b) N == 3 (mod 4) and -2 generates Z_p^* but +2 does not.
The A_1-primes are the odd T- or Twist-primes (the T-primes are the same as the Queneau-numbers, A054639). For the related A_0-, A^+_1- and A^-_1-primes, see A163777, A163779 and A163780. Considered as a set, the present sequence is the union of the A^+_1-primes (A163779) and the A^-_1-primes (A163780). It is also equal to the difference of A054639 and the A_0-primes (A163777).

P. R. J. Asveld, Table of n, a(n) for n=1..6706.
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers (2011), TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some Families of Permutations and Their Primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014.

Cf. A054639, A163777, A163779, A163780, A294434, A294673.

follow[s_, f_] := Module[{t, k}, t = f[s]; k = 1; While[t>s, k++; t = f[t]]; If[s == t, k, 0]];
okQ[n_] := n>1 && n == follow[1, Function[j, Ceiling[n/2] + (-1)^j*Ceiling[ (j-1)/2]]];
A163778 = Select[Range[1000], okQ] (* Jean-François Alcover, Jun 07 2018, after Andrew Howroyd *)

Follow(s, f)={my(t=f(s), k=1); while(t>s, k++; t=f(t)); if(s==t, k, 0)}
ok(n)={n>1 && n==Follow(1, j->ceil(n/2) + (-1)^j*ceil((j-1)/2))}
select(ok, [1..1000]) \\ Andrew Howroyd, Nov 11 2017

ok(n)={n>1 && n%2==1 && isprime(2*n+1) && znorder(Mod(2, 2*n+1)) == if(n%4==3, n, 2*n)}
select(ok, [1..1000]) \\ Andrew Howroyd, Nov 11 2017

a(33)-a(55) from Andrew Howroyd, Nov 11 2017

New name from Joerg Arndt, Mar 23 2018

A163780 Terms in A054639 equal to 3 mod 4.

Original entry on oeis.org

3, 11, 23, 35, 39, 51, 83, 95, 99, 119, 131, 135, 155, 179, 183, 191, 231, 239, 243, 251, 299, 303, 323, 359, 371, 375, 411, 419, 431, 443, 483, 491, 495, 515, 519, 531, 543, 575, 611, 615, 639, 651, 659, 683, 719, 723, 743, 755, 771, 779, 783, 791, 803, 831, 879

Offset: 1

Peter R. J. Asveld, Aug 12 2009

nonn

Previous name was: a(n) is the n-th A^-_1-prime (Archimedes^-_1 prime).

N is A^-_1-prime iff N=3 (mod 4), p=2N+1 is a prime number and -2 generates Z_p^* (the multiplicative group of Z_p) but +2 does not.

P. R. J. Asveld Table of n, a(n) for n=1..3378.
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers (2011), TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some Families of Permutations and Their Primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014.

The A^-_1-primes are the T- or Twist-primes congruent 3 (mod 4), these T-primes are equal to the Queneau-numbers (A054639). For the related A_0-, A_1- and A^+_1-primes, see A163777, A163778 and A163779. Considered as sets the union of A163779 and A163780 equals A163778, the union of A163780 and A163777 is equal to A163781 (dual J_2-primes).

ok(n) = n%4==3 && isprime(2*n+1) && znorder(Mod(2, 2*n+1)) == n;
select(ok, [1..1000]) \\ Andrew Howroyd, Nov 11 2017

a(33)-a(55) from Andrew Howroyd, Nov 11 2017

New name from Andrey Zabolotskiy, Mar 23 2018

A163779 Numbers k of the form 4j + 1 such that 2k + 1 is a prime with primitive root 2.

Original entry on oeis.org

1, 5, 9, 29, 33, 41, 53, 65, 69, 81, 89, 105, 113, 173, 189, 209, 221, 233, 245, 261, 273, 281, 293, 309, 329, 393, 413, 429, 441, 453, 473, 509, 545, 561, 585, 593, 629, 641, 645, 653, 713, 725, 741, 749, 761, 765, 785, 809, 833, 873, 893, 933, 953, 965, 989, 993

Offset: 1

Peter R. J. Asveld, Aug 12 2009

nonn

Previous name was: a(n) is the n-th A^+_1-prime (Archimedes^+_1 prime).

N is A^+_1-prime iff N=1 (mod 4), p=2N+1 is a prime number and +2 generates Z_p^* (the multiplicative group of Z_p) but -2 does not.

Joerg Arndt, Table of n, a(n) for n = 1..10000 (first 3328 from P. R. J. Asveld)
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers (2011), TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some Families of Permutations and Their Primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014.
P. Michael Hutchins, Reworded Definition

The A^+_1-primes are the T- or Twist-primes congruent 1 (mod 4), these T-primes are equal to the Queneau-numbers (A054639). For the related A_0-, A_1- and A^-_1-primes, see A163777, A163778 and A163780. Considered as sets the union of A163779 and A163780 equals A163778, the union of A163779 and A163777 is equal to A163782 (J_2-primes).

okQ[n_] := Mod[n, 4] == 1 && PrimeQ[2n+1] && MultiplicativeOrder[2, 2n+1] == 2n;
Select[Range[1000], okQ] (* Jean-François Alcover, Jun 30 2018, after Andrew Howroyd *)

ok(n) = n%4==1 && isprime(2*n+1) && znorder(Mod(2, 2*n+1))==2*n;
select(ok, [1..1000]) \\ Andrew Howroyd, Nov 11 2017

2 * a(n) + 1 = A213051(n+1). - Joerg Arndt, Mar 23 2018

a(32)-a(55) from Andrew Howroyd, Nov 11 2017

Term 1 prepended and new name from Joerg Arndt, Mar 23 2018

A163781 a(n) is the n-th dJ_2 prime (dual Josephus_2 prime).

Original entry on oeis.org

2, 3, 6, 11, 14, 18, 23, 26, 30, 35, 39, 50, 51, 74, 83, 86, 90, 95, 98, 99, 119, 131, 134, 135, 146, 155, 158, 174, 179, 183, 186, 191, 194, 210, 230, 231, 239, 243, 251, 254, 270, 278, 299, 303, 306, 323, 326, 330, 338, 350, 354, 359, 371, 375, 378

Offset: 1

Peter R. J. Asveld, Aug 17 2009

nonn

The family of dual Josephus_2 (or dJ_2) permutations is defined by p(m,N)=(2N + 1 - F(m,2N + 1))/2 if 1<=m<=N, N>=2, where F(x,y) is the odd number such that 1<=F(x,y)=0. Note that F(2k + 1,y)=2k + 1 for 2k + 1

dJ_2 permutations can also be defined using a numbering/elimination procedure similar to the definition of the Josephus_2 permutations in [R.L. Graham et al.], or in A163782; see [P. R. J. Asveld].

No formula is known for a(n): the dJ_2 primes have been found by exhaustive search. But we have: (1) N is dJ_2 prime iff p=2N+1 is a prime number and -2 generates Z_p^* (the multiplicative group of Z_p); (2) N is dJ_2 prime iff p=2N+1 is a prime number and exactly one of the following holds:

(a) N=2 (mod 4) and both +2 and -2 generate Z_p^*,

(b) N=3 (mod 4) and -2 generates Z_p^* but +2 does not.

			For N=6 we have
  m       | 1   2   3   4   5   6
  --------+----------------------
  F(m,13) | 1   7   3  11   5   9
  t       | 0   2   0   1   0   3
  p(m,6)  | 6   3   5   1   4   2
So the permutation is (1 6 2 3 5 4) and 6 is dJ_2 prime.

R. L. Graham, D. E. Knuth & O. Patashnik, Concrete Mathematics (1989), Addison-Wesley, Reading, MA. Sections 1.3 & 3.3.

P. R. J. Asveld, Table of n, a(n) for n=1..6756
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers (2011), TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some Families of Permutations and Their Primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014. University link.
Index entries for sequences related to the Josephus Problem

Considered as sets the union of A163781 and A163782 (J_2 primes) equals A054639 (T-primes or Queneau numbers), their intersection is equal to A163777 (Archimedes_0 primes). A163781 equals the union of A163777 and A163780 (Archimedes^-_1 primes).

okQ[n_] := Mod[n, 4] >= 2 && PrimeQ[2n+1] && MultiplicativeOrder[2, 2n+1] == If[OddQ[n], n, 2n];
Select[Range[1000], okQ] (* Jean-François Alcover, Sep 23 2019, from PARI *)

ok(n)={n%4>=2 && isprime(2*n+1) && znorder(Mod(2, 2*n+1)) == if(n%2,n,2*n)};
select(ok, [1..1000]) \\ Andrew Howroyd, Nov 11 2017

a(37)-a(55) from Andrew Howroyd, Nov 11 2017

A019567 Order of the Mongean shuffle permutation of 2n cards: a(n) is least number m for which either 2^m + 1 or 2^m - 1 is divisible by 4n + 1.

Original entry on oeis.org

1, 2, 3, 6, 4, 6, 10, 14, 5, 18, 10, 12, 21, 26, 9, 30, 6, 22, 9, 30, 27, 8, 11, 10, 24, 50, 12, 18, 14, 12, 55, 50, 7, 18, 34, 46, 14, 74, 24, 26, 33, 20, 78, 86, 29, 90, 18, 18, 48, 98, 33, 10, 45, 70, 15, 24, 60, 38, 29, 78, 12, 84, 41, 110, 8, 84, 26, 134, 12, 46, 35, 36, 68, 146

Offset: 0

John Bullitt (metta(AT)world.std.com), N. J. A. Sloane and J. H. Conway

Write down 1, then 2 to left, 3 to right, 4 to left, ..., getting [ 2n,2n-2,...,4,2,1,3,5,...,2n-1 ]; the sequence 2,3,6,4,6,10,14,5,18,10,12,21,26,9,... gives order of permutation sending 1 to 2n, 2 to 2n-2, ..., 2n to 2n-1.
Equivalently, the sequence 2,3,6,4,6,10,14,5,18,10,12,21,26,9,... gives the number of Mongean shuffles needed to return a deck of 2n cards (n=1,2,3,...) to its original order.
It appears that a(n) = order((-1)^(n+1)*2 in Z_{2n+1}) / f with f=1 when n==2 (mod 3) and for n = 0, 19, 21, 30,33, 52, 55, 61, 63, 70, ..., f=2 else. I don't know how to characterize the "exceptional" n's. - M. F. Hasler, Mar 31 2019

			Illustrating the initial terms:
   n  4n+1  2^m+1  2^m-1  m
   0    1            1    1
   1    5     5           2
   2    9     9           3
   3   13    5*13         6
   4   17     17          4
   5   21           3*21  6
   6   25   41*25        10

A. P. Domoryad, Mathematical Games and Pastimes, Pergamon Press, 1964; see pp. 134-135.
W. W. Rouse Ball, Mathematical Recreations and Essays, 11th ed. 1939, p. 311

R. J. Mathar, Table of n, a(n) for n = 0..2000
P. Diaconis, The mathematics of perfect shuffles, Adv. Appl. Math. 4 (2) (1983) 175-196.
Arne Ledet, The Monge shuffle for two-power decks, Math. Scand. Vol 98, No 1 (2006), 5-11.
E. Ross, Mathematics and Music: The Mathieu Group M_12 (2011), Chapter 2.
T. & X. Vigouroux, First 2000000 terms, for n = 0..1999999

Cf. A163777, A238371, A294673.

A019567:=  proc(n)
    for m from 1 do
        if modp(2^m-1,4*n+1) =0 or modp(2^m+1,4*n+1)=0 then
            return m ;
        end if;
    end do;
end proc: # N. J. A. Sloane, Jul 28 2007

a[n_] := For[m=1, True, m++, If[AnyTrue[{-1, 1}, Divisible[2^m+#, 4n+1]&], Return[m]]];
Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Aug 26 2019 *)

A019567(n,z=Mod(2,4*n+1))=for(m=1,oo,bittest(5,lift(z^m+1))&&return(m)) \\ M. F. Hasler, Mar 31 2019

a(A163777(n)/2) = A163777(n). - Andrew Howroyd, Nov 11 2017

Comments corrected by Mikko Nieminen, Jul 26 2007, who also provided the Domoryad reference

Definition edited by N. J. A. Sloane, Nov 09 2017

A163776 a(n) is the n-th dS-prime (dual Shuffle prime).

Original entry on oeis.org

4, 6, 12, 22, 28, 36, 46, 52, 60, 70, 78, 100, 102, 148, 166, 172, 180, 190, 196, 198, 238, 262, 268, 270, 292, 310, 316, 348, 358, 366, 372, 382, 388, 420, 460, 462, 478, 486, 502, 508, 540, 556, 598, 606, 612, 646, 652, 660, 676, 700, 708, 718, 742, 750, 756

Offset: 1

Peter R. J. Asveld, Aug 13 2009

nonn

For N>=2, the family of dual shuffle permutations is defined by p(m,N) = -2m (mod N+1) if N is even, p(m,N) = -2m (mod N) if N is odd and 1<=m

No formula is known for a(n): the dS-primes have been found by exhaustive search. But we have: N is dS-prime iff p=N+1 is an odd prime number and -2 generates Z_p^* (the multiplicative group of Z_p).

			For N=6 and N=10 we obtain the permutations (1 5 4 6 2 3) and (1 9 4 3 5)(2 7 8 6 10): 6 is dS-prime, but 10 is not.

P. R. J. Asveld, Table of n, a(n) for n=1..3612
P. R. J. Asveld, Permuting operations on strings and their relation to prime numbers, Discrete Applied Mathematics 159 (2011) 1915-1932.
P. R. J. Asveld, Permuting operations on strings and the distribution of their prime numbers (2011), TR-CTIT-11-24, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Some Families of Permutations and Their Primes (2009), TR-CTIT-09-27, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
P. R. J. Asveld, Permuting Operations on Strings-Their Permutations and Their Primes, Twente University of Technology, 2014. University link.
Index entries for sequences related to the Josephus Problem

a(n)/2 results in the dual Josephus_2-primes (A163781). Considered as sets a(n)/2 is the union of A163777 and A163780. If b(n) denotes the shuffle primes (A071642), then the union of a(n)/2 and b(n)/2 is equal to the Twist-primes or Queneau numbers (A054639), their intersection is equal to the Archimedes_0-primes (A163777).

a(n) = 2*A163781(n).

a(33)-a(55) from Andrew Howroyd, Nov 11 2017

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A163782 a(n) is the n-th J_2-prime (Josephus_2 prime).

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A071642 Numbers n such that x^n + x^(n-1) + x^(n-2) + ... + x + 1 is irreducible over GF(2).

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A054639 Queneau numbers: numbers n such that the Queneau-Daniel permutation {1, 2, 3, ..., n} -> {n, 1, n-1, 2, n-2, 3, ...} is of order n.

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A163778 Odd terms in A054639.

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A163780 Terms in A054639 equal to 3 mod 4.

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A163779 Numbers k of the form 4*j + 1 such that 2*k + 1 is a prime with primitive root 2.

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A163781 a(n) is the n-th dJ_2 prime (dual Josephus_2 prime).

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A163779 Numbers k of the form 4j + 1 such that 2k + 1 is a prime with primitive root 2.