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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A058950 Coefficients of monic primitive irreducible polynomials over GF(5) listed in lexicographic order.

Original entry on oeis.org

12, 13, 112, 123, 133, 142, 1032, 1033, 1042, 1043, 1102, 1113, 1143, 1203, 1213, 1222, 1223, 1242, 1302, 1312, 1322, 1323, 1343, 1403, 1412, 1442, 10122, 10123, 10132, 10133, 10412, 10413, 10442, 10443, 11013, 11023, 11032, 11042, 11113
Offset: 1

Views

Author

N. J. A. Sloane, Jan 13 2001

Keywords

Crossrefs

Cf. A058945.
Irreducible over GF(2), GF(3), GF(4), GF(5), GF(7): A058943, A058944, A058948, A058945, A058946. Primitive irreducible over GF(2), GF(3), GF(4), GF(5), GF(7): A058947, A058949, A058952, A058950, A058951.

Programs

  • Mathematica
    car = 5; maxDegree = 5;
    okQ[coefs_List] := Module[{P}, P = coefs.x^Range[Length[coefs] - 1, 0, -1]; coefs[[1]] == 1 && IrreduciblePolynomialQ[P, Modulus -> car] && PrimitivePolynomialQ[P, car]];
    FromDigits /@ Select[Table[IntegerDigits[k, car], {k, car+1, car^(maxDegree + 1)}], okQ] (* Jean-François Alcover, Sep 10 2019 *)

Extensions

More terms from Jean Gaumont (jeangaum87(AT)yahoo.com), Apr 16 2006

A058951 Coefficients of monic primitive irreducible polynomials over GF(7) listed in lexicographic order.

Original entry on oeis.org

12, 14, 113, 123, 125, 135, 145, 153, 155, 163, 1032, 1052, 1062, 1112, 1124, 1152, 1154, 1214, 1242, 1262, 1264, 1304, 1314, 1322, 1334, 1352, 1354, 1362, 1422, 1432, 1434, 1444, 1504, 1524, 1532, 1534, 1542, 1552, 1564, 1604, 1612, 1632, 1644, 1654
Offset: 1

Views

Author

N. J. A. Sloane, Jan 13 2001

Keywords

Crossrefs

Cf. A058946.
Irreducible over GF(2), GF(3), GF(4), GF(5), GF(7): A058943, A058944, A058948, A058945, A058946. Primitive irreducible over GF(2), GF(3), GF(4), GF(5), GF(7): A058947, A058949, A058952, A058950, A058951.

Programs

  • Mathematica
    car = 7; maxDegree = 4;
    okQ[coefs_List] := Module[{P}, P = coefs.x^Range[Length[coefs] - 1, 0, -1]; coefs[[1]] == 1 && IrreduciblePolynomialQ[P, Modulus -> car] && PrimitivePolynomialQ[P, car]];
    FromDigits /@ Select[Table[IntegerDigits[k, car], {k, car+1, car^(maxDegree + 1)}], okQ] (* Jean-François Alcover, Sep 10 2019 *)

Extensions

More terms from Jean Gaumont (jeangaum87(AT)yahoo.com), Apr 16 2006

A059912 Triangle T(n,k) of orders of n degree irreducible polynomials over GF(2) listed in ascending order, k=1..A059499(n).

Original entry on oeis.org

1, 3, 7, 5, 15, 31, 9, 21, 63, 127, 17, 51, 85, 255, 73, 511, 11, 33, 93, 341, 1023, 23, 89, 2047, 13, 35, 39, 45, 65, 91, 105, 117, 195, 273, 315, 455, 585, 819, 1365, 4095, 8191, 43, 129, 381, 5461, 16383, 151, 217, 1057, 4681, 32767, 257, 771, 1285, 3855
Offset: 1

Views

Author

Vladeta Jovovic, Feb 09 2001

Keywords

Comments

A permutation of the odd positive numbers; namely, order each odd number d by the multiplicative order of 2 modulo d (in case of a tie, smaller d go first). - Jeppe Stig Nielsen, Feb 13 2020

Examples

			There are 18 (cf. A001037) irreducible polynomials of degree 7 over GF(2) which all have order 127.
Triangle T(n,k) begins:
    1;
    3;
    7;
    5,   15;
   31;
    9,   21,  63;
  127;
   17,   51,  85, 255;
   73,  511;
   11,   33,  93, 341, 1023;
  ...
		

Crossrefs

Column k=1 of A212737.
Column k=1 gives: A212953.
Last elements of rows give: A000225.
Cf. A108974.

Programs

  • Maple
    with(numtheory):
    M:= proc(n) option remember;
          divisors(2^n-1) minus U(n-1)
        end:
    U:= proc(n) option remember;
          `if`(n=0, {}, M(n) union U(n-1))
        end:
    T:= n-> sort([M(n)[]])[]:
    seq(T(n), n=1..20);  # Alois P. Heinz, May 31 2012
  • Mathematica
    m[n_] := m[n] = Complement[ Divisors[2^n - 1], u[n - 1]]; u[0] = {}; u[n_] := u[n] = Union[ m[n], u[n - 1]]; t[n_, k_] := m[n][[k]]; Flatten[ Table[t[n, k], {n, 1, 16}, {k, 1, Length[ m[n] ]}]] (* Jean-François Alcover, Jun 14 2012, after Alois P. Heinz *)
  • PARI
    maxDegree=26;for(n=1,maxDegree,forstep(d=1,2^n,2,znorder(Mod(2,d))==n&&print1(d,", "))) \\ inefficient, Jeppe Stig Nielsen, Feb 13 2020

Formula

T(n,k) = k-th smallest element of M(n) = {d : d|(2^n-1)} \ U(n-1) with U(n) = M(n) union U(n-1) if n>0, U(0) = {}. - Alois P. Heinz, Jun 01 2012

A169887 Primes in carryless arithmetic mod 10.

Original entry on oeis.org

21, 23, 25, 27, 29, 41, 43, 45, 47, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 63, 65, 67, 69, 81, 83, 85, 87, 89, 201, 209, 227, 229, 241, 243, 261, 263, 287, 289, 403, 407, 421, 427, 443, 449, 463, 469, 481, 487, 551, 553, 557, 559, 603, 607, 623, 629, 641, 647, 661, 667, 683, 689, 801, 809, 821, 823, 847, 849, 867, 869, 881, 883
Offset: 1

Views

Author

Keywords

Comments

Define the units in carryless arithmetic mod 10 to be the numbers 1, 3, 7 and 9 (these divide any number). A prime is a number N, not a unit, whose only factorizations are of the form N = u * M, where u is a unit.
There are two types: e-type primes (A163396) and f-type (A169984).

Examples

			Examples of nonprimes: 2 = 2*51, 4 = 2*2, 10 = 52*85, 11 = 57*83, 101 = 13*17, 102 = 58 * 254 = 502 * 801, 103 = 53 * 251 = 507 * 809, 107 = 53 * 259 = 507 * 801, 108 = 58 * 256 = 502 * 809, 111 = 227 * 553.
		

Crossrefs

Cf. A004520, A059729, A168294, A168541, A169885, A169886, A169884, A169903 (primitive primes).
Cf. A169962.

A059478 Arrange irreducible polynomials over GF(2) in lexicographic order and write down the order of each polynomial.

Original entry on oeis.org

1, 1, 3, 7, 7, 15, 15, 5, 31, 31, 31, 31, 31, 31, 63, 9, 21, 63, 63, 63, 63, 63, 21, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 51, 255, 255, 255, 17, 85, 255, 255, 255, 255, 255, 255, 85, 85, 255, 85, 255, 51, 85, 255
Offset: 1

Views

Author

Vladeta Jovovic, Feb 03 2001

Keywords

References

  • R. Lidl and H. Niederreiter, Finite Fields, Addison-Wesley, 1983.

Crossrefs

A059913 Triangle T(n,k) of numbers of n degree irreducible polynomials over GF(2) which have order A059912(n,k), k=1..A059499(n).

Original entry on oeis.org

2, 1, 2, 1, 2, 6, 1, 2, 6, 18, 2, 4, 8, 16, 8, 48, 1, 2, 6, 30, 60, 2, 8, 176, 1, 2, 2, 2, 4, 6, 4, 6, 8, 12, 12, 24, 24, 36, 48, 144, 630, 3, 6, 18, 378, 756, 10, 12, 60, 300, 1800, 16, 32, 64, 128, 256, 512, 1024, 2048, 7710, 1, 1, 2, 6, 6, 6, 8, 12, 18, 24
Offset: 1

Views

Author

Vladeta Jovovic, Feb 09 2001

Keywords

Comments

Row sums give A001037.

Examples

			There are 9 (cf. A001037) irreducible polynomials of degree 6 over GF(2): 1 of order 9, 2 of order 21 and 6 of order 63 (cf. A059912).
Triangle T(n,k) begins:
  2;
  1;
  2;
  1,  2;
  6;
  1,  2,   6;
  18;
  2,  4,   8, 16;
  8, 48;
  1,  2,   6, 30, 60;
  2,  8, 176;
  ...
		

Crossrefs

Programs

  • Mathematica
    Prepend[Table[Map[EulerPhi[#]/n &, Complement[Divisors[2^n - 1],Union[Flatten[Table[Divisors[2^k - 1], {k, 1, n - 1}]]]]], {n, 2,20}], {2}] // Grid (* Geoffrey Critzer, Dec 02 2019 *)

Formula

T(n,k) = phi(A059912(n,k))/n, where phi = Euler totient function A000010.

A169903 Primitive primes in carryless arithmetic mod 10.

Original entry on oeis.org

21, 23, 25, 27, 29, 51, 56, 201, 209, 227, 229, 241, 243, 261, 263, 287, 289, 551, 2023, 2027, 2043, 2047, 2061, 2069, 2081, 2089, 2207, 2209, 2221, 2223, 2263, 2267, 2281, 2287, 2401, 2407, 2421, 2423, 2441, 2449, 2483, 2489, 2603, 2609
Offset: 1

Views

Author

Keywords

Comments

Define the units in carryless arithmetic mod 10 to be the numbers 1, 3, 7 and 9 (these divide any number). A prime is a number N, not a unit, whose only factorizations are of the form N = u * M, where u is a unit.
A prime is primitive if it is not the carryless product of a smaller prime and a unit.
A subsequence of A169887.

Crossrefs

A091254 Reducible polynomials over GF(2) in binary format.

Original entry on oeis.org

100, 101, 110, 1000, 1001, 1010, 1100, 1110, 1111, 10000, 10001, 10010, 10100, 10101, 10110, 10111, 11000, 11010, 11011, 11100, 11101, 11110, 100000, 100001, 100010, 100011, 100100, 100110, 100111, 101000, 101010, 101011, 101100
Offset: 1

Views

Author

Antti Karttunen, Jan 03 2004

Keywords

Crossrefs

a(n) = A007088(A091242(n)). Cf. A058943.

A065020 Coefficients of irreducible polynomials over GF(3) listed in lexicographic order.

Original entry on oeis.org

2, 11, 12, 20, 101, 112, 122, 200, 1021, 1022, 1102, 1112, 1121, 1201, 1211, 1222, 2000, 10012, 10022, 10102, 10111, 10121, 10202, 11002, 11021, 11101, 11111, 11122, 11222, 12002, 12011, 12101, 12112, 12121, 12212, 20000, 100021, 100022
Offset: 1

Views

Author

Robert G. Wilson v, Nov 01 2001

Keywords

Crossrefs

Cf. A058943.

Programs

  • Mathematica
    Do[a = Reverse[ IntegerDigits[n, gf]]; b = {0}; l = Length[a]; k = 1; While[k < l + 1, b = Append[b, a[[k]]*x^(k - 1)]; k++ ]; b = Apply[ Plus, b]; c = Factor[b, Modulus -> gf]; If[ !IntegerQ[ Log[ gf, n]] && b == c, Print[ FromDigits[ IntegerDigits[n, gf]]]], {n, 1, 300} ]

A071802 Table in which n-th row gives exponents (in decreasing order) of lexicographically earliest primitive irreducible polynomial of degree n over GF(2).

Original entry on oeis.org

1, 0, 2, 1, 0, 3, 1, 0, 4, 1, 0, 5, 2, 0, 6, 1, 0, 7, 1, 0, 8, 4, 3, 1, 0, 9, 1, 0, 10, 3, 0, 11, 2, 0, 12, 3, 0, 13, 4, 3, 1, 0, 14, 5, 0, 15, 1, 0, 16, 5, 3, 1, 0, 17, 3, 0, 18, 3, 0, 19, 5, 2, 1, 0, 20, 3, 0, 21, 2, 0, 22, 1, 0, 23, 5, 0, 24, 4, 3, 1, 0, 25, 3, 0, 26, 4, 3, 1, 0, 27, 5, 2, 1, 0
Offset: 1

Views

Author

N. J. A. Sloane, Jun 24 2002

Keywords

Examples

			x+1, x^2+x+1, x^3+x+1, x^4+x+1, x^5+x^2+1, ...
		

References

  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1978, p. 408.
  • M. Olofsson, VLSI Aspects on Inversion in Finite Fields, Dissertation No. 731, Dept Elect. Engin., Linkoping, Sweden, 2002.

Crossrefs

Cf. A058943.

Programs

  • Mathematica
    a = {}; Do[k = 2^n + 1; While[s = Apply[Plus, IntegerDigits[k, 2]*x^Table[i, {i, n, 0, -1}]]; k < 2^(n + 1) - 1 && Factor[s, Modulus -> 2] =!= s, k += 2]; a = Append[a, Reverse[ Exponent[ Apply[ Plus, IntegerDigits[k, 2]*x^Table[i, {i, n, 0, -1}]], x, List]]], {n, 1, 27}]; Flatten[a]

Extensions

Extended by Robert G. Wilson v, Jun 25 2002
Previous Showing 11-20 of 21 results. Next