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.

Showing 1-9 of 9 results.

A219324 Positive integers n that are equal to the determinant of the circulant matrix formed by the decimal digits of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 247, 370, 378, 407, 481, 518, 592, 629, 1360, 3075, 26027, 26933, 45018, 69781, 80487, 154791, 1920261, 2137616, 2716713, 3100883, 3480140, 3934896, 4179451, 4830936, 5218958, 11955168, 80651025, 95738203, 257059332, 278945612, 456790123, 469135802, 493827160, 494376160
Offset: 1

Views

Author

Max Alekseyev, Nov 17 2012

Keywords

Comments

Belukhov proved that if d is an odd divisor of p-1, then for integers q=(p^d-1)/((p-1)*d) and t such that (p-1)*(d-1)/2 < t < (p-1)*(d+1)/2 and gcd(t,d)=1, the number q*t equals the determinant of the circulant matrix formed by its base-p digits. For this sequence (where p=10), not every term can be obtained in this way.
If you rotate left (or take the absolute value of the determinant), then the sequence contains the following additional terms: 48, 1547, 123823, 289835, 23203827, ... (cf. A219326, A219327). - Robert G. Wilson v, Dec 12 2012
a(58) > 6*10^11. - Giovanni Resta, Dec 14 2012
See also A303260 for a different generalization: n X n circulant determinant having its base n+1 digits equal to a row. - M. F. Hasler, Apr 23 2018

Examples

			          | 2 4 7 |
247 = det | 7 2 4 |
          | 4 7 2 |
		

Crossrefs

Cf. A219325 (binary digits), A219326 (digits in reverse order), A219327 (absolute value of determinant), A306853 (permanent).
Cf. A303260.

Programs

  • Mathematica
    f[n_] := Det[ NestList[ RotateRight@# &, IntegerDigits@ n, Floor[ Log10[n] + 1] - 1]]; k = 1; lst = {}; While[k < 1120000000, a = f@ k; If[a == k, AppendTo[lst, k]]; k++]; lst (* Robert G. Wilson v, Nov 20 2012 *)
    Select[Range[53*10^5],Det[Table[RotateRight[IntegerDigits[#],d],{d,0,IntegerLength[ #]-1}]]==#&] (* The program generates the first 34 terms of the sequence. To generate more, increase the Range constant, but the program will take a long time to run. *) (* Harvey P. Dale, Jul 05 2021 *)
  • PARI
    { isA219324(n) = local(d,m,r); d=eval(Vec(Str(n))); m=#d; r=Mod(x,polcyclo(m)); prod(j=1,m,sum(i=1,m,d[i]*r^((i-1)*j)))==n }
    
  • Python
    from sympy import Matrix
    A219324_list = []
    for n in range(1,10**4):
        s = [int(d) for d in str(n)]
        m = len(s)
        if n == Matrix(m, m, lambda i, j: s[(i-j) % m]).det():
            A219324_list.append(n) # Chai Wah Wu, Oct 18 2021

A303367 Numbers equal to the determinant of a circulant matrix based on the base-7 digits of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 27, 81, 133, 143, 144, 152, 190, 209, 250, 1125, 8569, 10934, 16401, 237568, 362306, 391257, 695751, 723260, 5294625, 6056974, 6332291, 6523631, 6669475, 11128547, 12486285, 17417491, 18682225, 19429514, 19781014, 20924092, 21671381
Offset: 1

Views

Author

M. F. Hasler, May 05 2018

Keywords

Comments

Base 7 variant of A219327. See A303366 .. A303369 for other bases.

Examples

			133 is in the sequence because 133 = 250[7] (in base 7) and 133 = det [2,5,0; 0,2,5; 5,0,2].
		

Crossrefs

Cf. A303366 (base 6), A303368 (base 8), A303369 (base 9), A219327 (base 10).

Programs

  • PARI
    (c(v)=abs(matdet(matrix(#v,#v,i,j,v[(j-i)%#v+1]))));for(n=1,oo,n==c(digits(n,7))&&print1(n","))

Extensions

a(25)-a(37) from Giovanni Resta, May 07 2018

A303369 Numbers equal to the determinant of a circulant matrix based on the base-9 digits of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 104, 126, 130, 468, 2035, 8052, 8421, 12100, 18788, 21296, 60736, 90155, 109135, 119795, 123201, 137605, 147095, 160965, 199728, 457856, 523809, 697334, 2958176, 3652360, 4725030, 5331625, 6825024, 7014400, 7694336, 9376133, 14012352
Offset: 1

Views

Author

M. F. Hasler, May 05 2018

Keywords

Comments

Base 9 variant of A219327. See A303366 .. A303368 for other bases.

Examples

			104 is in the sequence because 104 = 125[9] (in base 9) and 104 = det [1,2,5; 5,1,2; 2,5,1].
		

Crossrefs

Cf. A303366 (base 6), A303367 (base 7), A303368 (base 8), A219327 (base 10).

Programs

  • PARI
    (c(v)=abs(matdet(matrix(#v,#v,i,j,v[(j-i)%#v+1]))));for(n=1,oo,n==c(digits(n,9))&&print1(n","))

Extensions

a(31)-a(39) from Giovanni Resta, May 07 2018

A303368 Numbers equal to the determinant of a circulant matrix based on the base-8 digits of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 21, 133, 432, 525, 1200, 1456, 1904, 4774, 24583, 281048, 289820, 333293, 420239, 428752, 430686, 437554, 500380, 500888, 736600, 941578, 984377, 1027176, 1069975, 1112774, 1155573, 1662216, 1776201, 2087008, 3212235, 7928375, 8131725
Offset: 1

Views

Author

M. F. Hasler, May 05 2018

Keywords

Comments

Base 8 variant of A219327.

Crossrefs

Cf. A303367 (base 7), A303369 (base 9), A219327 (base 10).

Programs

  • PARI
    (c(v)=abs(matdet(matrix(#v,#v,i,j,v[(j-i)%#v+1]))));for(n=1,oo,n==c(digits(n,8))&&print1(n","))

Extensions

a(33)-a(38) from Giovanni Resta, May 07 2018

A303366 Numbers equal to the determinant of a circulant matrix based on the base-6 digits of n.

Original entry on oeis.org

1, 2, 3, 4, 5, 320, 1936, 2761, 3421, 3732, 4043, 4354, 1697296, 2121620, 2970268, 3076349, 5222639, 8979475, 41657517, 63095140, 110416495, 488553143, 646839439, 1066194997, 1209597525, 1803581465, 1861934400, 2019744271, 2691271467, 2842031031, 3052726590, 7100897730, 10806417998
Offset: 1

Views

Author

M. F. Hasler, May 05 2018

Keywords

Comments

Base 6 variant of A219327. See A303367 .. A303369 for other bases.

Examples

			320 is in the sequence because 320 = 1252[6] (in base 6) and 320 = det [1,2,5,2; 2,1,2,5; 5,2,1,2; 2,5,2,1].
		

Crossrefs

Cf. A303367 (base 7), A303368 (base 8), A303369 (base 9), A219327 (base 10).

Programs

  • Mathematica
    Select[Range[5000],#==Det[NestList[RotateRight,IntegerDigits[#,6],IntegerLength[#,6]-1]]&] (* The program generates the first 12 terms of the sequence. *) (* Harvey P. Dale, Mar 11 2024 *)
  • PARI
    (c(v)=abs(matdet(matrix(#v,#v,i,j,v[(j-i)%#v+1]))));for(n=1,oo,n==c(digits(n,6))&&print1(n","))

Extensions

a(13)-a(33) from Giovanni Resta, May 07 2018

A306853 Positive integers equal to the permanent of the circulant matrix formed by their decimal digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 261, 370, 407, 52036, 724212, 223123410
Offset: 1

Views

Author

Paolo P. Lava, Mar 13 2019

Keywords

Comments

1, 2, 3, 4, 5, 6, 7, 8, 9, 370 and 407 are also equal to the determinant of the circulant matrix formed by their decimal digits.

Examples

			     | 2 6 1 |
perm | 1 2 6 | = 2*2*2 + 6*6*6 + 1*1*1 + 1*2*6 + 6*1*2 + 2*6*1 = 261.
     | 6 1 2 |
.
     | 2 2 3 1 2 3 4 1 0 |
     | 0 2 2 3 1 2 3 4 1 |
     | 1 0 2 2 3 1 2 3 4 |
     | 4 1 0 2 2 3 1 2 3 |
perm | 3 4 1 0 2 2 3 1 2 | = 223123410
     | 2 3 4 1 0 2 2 3 1 |
     | 1 2 3 4 1 0 2 2 3 |
     | 3 1 2 3 4 1 0 2 2 |
     | 2 3 1 2 3 4 1 0 2 |
		

Crossrefs

Up to n=110 the permanent of the circulant matrix of the digits of n is equal to A101337 but from n=111 on it can differ.

Programs

  • Maple
    with(linalg): P:=proc(q) local a, b, c, d, i, j, k, n, t;
    for n from 1 to q do d:=ilog10(n)+1; a:=convert(n, base, 10); c:=[];
    for k from 1 to nops(a) do c:=[op(c), a[-k]]; od; t:=[op([]), c];
    for k from 2 to d do b:=[op([]), c[nops(c)]];
    for j from 1 to nops(c)-1 do b:=[op(b), c[j]]; od;
    c:=b; t:=[op(t), c]; od; if n=permanent(t)
    then print(n); fi; od; end: P(10^7);
  • PARI
    mpd(n) = {my(d = digits(n)); matpermanent(matrix(#d, #d, i, j, d[1+lift(Mod(j-i, #d))]));}
    isok(n) = mpd(n) == n; \\ Michel Marcus, Mar 14 2019
    
  • Python
    from sympy import Matrix
    A306853_list = []
    for n in range(1,10**6):
        s = [int(d) for d in str(n)]
        m = len(s)
        if n == Matrix(m, m, lambda i, j: s[(i-j) % m]).per():
            A306853_list.append(n) # Chai Wah Wu, Oct 18 2021

Extensions

a(15) from Vaclav Kotesovec, Aug 19 2021

A303261 Numbers having n digits in base n+1, and equal to the determinant of a circulant matrix based on these digits.

Original entry on oeis.org

1, 28, 35, 1936, 2761, 3421, 3732, 4043, 4354, 281048, 289820, 333293, 420239, 428752, 430686, 437554, 500380, 500888, 736600, 941578, 984377, 1027176, 1069975, 1112774, 1155573, 1662216, 1776201, 2087008, 5331625, 6825024, 7014400
Offset: 1

Views

Author

M. F. Hasler, Apr 25 2018

Keywords

Comments

A subsequence of A303262, namely, the terms in row n which correspond to n-digit numbers in base n+1.

Crossrefs

Programs

  • PARI
    for(n=1, 10, for(k=(n+1)^(n-1), (n+1)^n-1, d=Vec(digits(k, n+1)); abs(matdet(matrix(n, n, i, j, d[(j-i)%n+1])))==k&&print1(k", ")))

A303262 Table where row n lists numbers N equal to the determinant of an n X n circulant having as a row the base n+1 digits of N.

Original entry on oeis.org

1, 1, 1, 8, 9, 28, 35, 1, 65, 80, 91, 1, 44, 99, 550, 854, 1936, 2761, 3421, 3732, 4043, 4354, 1, 63, 65, 2527, 3311, 3969, 4095, 13545, 13889, 1, 128, 129, 145, 6066, 16384, 16385, 16512, 16513, 16641, 18560, 18577, 18669, 18705, 90738, 103759, 103965, 109220, 120142, 121920
Offset: 1

Views

Author

M. F. Hasler, Apr 23 2018

Keywords

Examples

			The table starts
(n=1) 1,
(n=2) 1,
(n=3) 1, 8, 9, 28, 35,
(n=4) 1, 65, 80, 91,
(n=5) 1, 44, 99, 550, 854, 1936, 2761, 3421, 3732, 4043, 4354,
(n=6) 1, 63, 65, 2527, 3311, 3969, 4095, 13545, 13889,
(n=7) 1, 128, 129, 145, 6066, 16384, 16385, 16512, 16513, 16641, 18560, 18577, 18669, 18705, 90738, 103759, 103965, ...
For example, T(3,1) = 1 because the determinant of the circulant starting with [0, 0, 1] is 1. For the same reason each row starts with 1.
T(3,2) = 8 = 020[4] (digits in base 4) = det(circulant([0, 2, 0])).
T(3,5) = 35 = 203[4] = det(circulant([2, 0, 3])).
		

Crossrefs

Programs

  • PARI
    for(n=1,7,for(k=1,(n+1)^n-1,d=Vec(digits(k,n+1),-n);abs(matdet(matrix(n,n,i,j,d[(j-i)%n+1])))==k&&print1(k",")))

A348428 Positive integers m that are equal to the determinant of the left circulant matrix formed by the decimal digits of m.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 1547, 26027, 26933, 45018, 69781, 80487, 154791, 23203827, 257059332, 278945612, 456790123, 469135802, 493827160, 494376160, 506172839, 530864197, 543209876, 897163795, 1662971175, 2293668391, 3880266075, 6473710191
Offset: 1

Views

Author

Chai Wah Wu, Oct 18 2021

Keywords

Comments

A left circulant matrix is also called a anti-circulant or (-1)-circulant matrix.
Subsequence of A219327.
Fixed points of A177894. - John Keith, Oct 24 2021

Examples

			           ⎡1  5  4  7⎤
1547 = det ⎢5  4  7  1⎥
           ⎢4  7  1  5⎥
           ⎣7  1  5  4⎦.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[10^6], Equal[Det[NestList[RotateLeft, #2, #3 - 1]], #1] & @@ {#1, #2, Length[#2]} & @@ {#, IntegerDigits[#]} &] (* Michael De Vlieger, Oct 18 2021 *)
  • PARI
    isok(m) = {my(d=digits(m), x); matdet(matrix(#d, #d, i, j, if (i==1, d[j], x = lift(Mod(j+i-1, #d)); if (!x, x += #d); d[x]))) == m;} \\ Michel Marcus, Oct 19 2021
  • Python
    from sympy import Matrix
    A348428_list = []
    for n in range(1,10**6):
        s = [int(d) for d in str(n)]
        m = len(s)
        if n == Matrix(m, m, lambda i, j: s[(i+j) % m]).det():
            A348428_list.append(n)
    
Showing 1-9 of 9 results.