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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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

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Author

Peter R. J. Asveld, Aug 13 2009

Keywords

Comments

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).

Examples

			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.
		

Crossrefs

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).

Formula

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

Extensions

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

A123399 Orders of "Gray" fields.

Original entry on oeis.org

1, 2, 3, 5, 6, 9, 11, 14, 23, 26, 29, 30, 33, 35, 39, 41, 51, 53, 65, 69, 74, 81, 83, 86, 89, 90, 95, 105, 113, 119, 131, 135, 146, 155, 158, 173, 179, 183, 189, 191, 209, 210, 221, 230, 231, 233, 239, 243, 245, 251, 254, 261, 273, 281, 293, 299, 303, 306, 309, 323, 326, 329, 330, 359, 371, 375, 386, 398, 411, 413, 419
Offset: 1

Author

N. J. A. Sloane, Oct 15 2006

Keywords

Comments

Numbers n such that there is a type-2 optimal normal basis over GF(2) and the corresponding polynomial is primitive. Subsequence of A054639. [Joerg Arndt, Apr 28 2012]

References

  • D. E. Knuth, The Art of Computer Programming, Section 7.2.1.1, Problem 31.

Crossrefs

Cf. A054639.

Formula

Let c_1(x) = x+1, c_2(x) = x^2+x+1, c_{j+1}(x) = x*c_j(x) + c_{j-1}(x) be polynomials over GF(2). Then n is in the sequence iff c_n(x) is a primitive irreducible polynomial.

Extensions

Terms >=105 by Joerg Arndt, Apr 28 2012.

A136250 Numbers n such that optimal normal basis exists for GF(2^n) over GF(2).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 9, 10, 11, 12, 14, 18, 23, 26, 28, 29, 30, 33, 35, 36, 39, 41, 50, 51, 52, 53, 58, 60, 65, 66, 69, 74, 81, 82, 83, 86, 89, 90, 95, 98, 99, 100, 105, 106, 113, 119, 130, 131, 134, 135, 138, 146, 148, 155, 158, 162, 172, 173, 174, 178, 179, 180, 183, 186
Offset: 1

Author

Joerg Arndt, Mar 17 2008

Keywords

Comments

An optimal normal basis for GF(2^n) is either of type-1 (A071642) or type-2 (A054639).

Crossrefs

Cf. A071642 and A054639.

Extensions

Edited by N. J. A. Sloane, Apr 08 2008

A014109 Number of possible circular rhymes of n strophes.

Original entry on oeis.org

1, 2, 3, 5, 9, 11, 14, 18, 23, 26, 29, 30, 33, 35, 39, 41
Offset: 1

Author

Simon Plouffe, Paul Simon (paulsimn(AT)mail.odyssee.net)

Keywords

Comments

Adding 6 to the sequence results in the first few Queneau numbers A054639. The entries a(n) are the first few generalizations of a verse form called sextine (or sestina in Italian) excluding the original sextine which was based on the number 6. The Queneau numbers characterize all these generalizations (including the number 6). For references see A054639.

References

  • From the OULIPO group (including Raymond Queneau), see OULIPO, Atlas de Littérature Potentielle, Coll. Idées, Gallimard, 1981, pp. 432, esp. p. 49.

Crossrefs

Cf. A054639.
Previous Showing 11-14 of 14 results.