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 1-7 of 7 results.

A143717 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2-3, 2-2-5, 2-3-7, 2-3-3, 2-2-5, 11-2-2, 3-13-2, 7-3-5,..)).

Original entry on oeis.org

4, 5, 8, 4, 5, 7, 12, 1, 19, 3, 15, 5, 32, 4, 1, 7, 7, 24, 28, 9, 20, 3, 36, 20, 8, 38, 47, 11, 4, 68, 5, 3, 0, 13, 42, 5, 6, 15, 86, 3, 58, 26, 1, 10, 75, 17, 22, 73, 4, 73, 29, 2, 1, 14, 73, 2, 122, 3, 15, 44, 24, 80, 4, 8, 24, 18, 16, 95, 7, 10, 5, 101, 117, 14, 9, 158, 3, 108, 9, 31
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 13 2008

Keywords

Examples

			Abs (7-3-5)=abs (-1) =1=a(8).
Abs (2-4-17)=abs(-19)=19=a(9).
Abs (2-3-2)=abs (-3)=3=a(10).
Abs (19-2-2)=abs 15=15=a(11),
Abs (5-3-7)=abs (-5)=5=a(12),
etc.
		

Crossrefs

Extensions

Replaced a 56 by a 1. R. J. Mathar, Feb 21 2009

A143852 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2-3-2, 2-5-2-3, 7-2-3-3, 2-2-5-11, 2-2-3-13, 2-7-3-5,..)).

Original entry on oeis.org

6, 8, 1, 16, 16, 13, 21, 20, 13, 34, 7, 17, 36, 37, 17, 27, 5, 13, 3, 29, 28, 6, 30, 8, 17, 66, 9, 1, 47, 52, 89, 8, 14, 77, 41, 81, 6, 31, 1, 1, 91, 8, 124, 13, 31, 13, 82, 17, 55, 69, 103, 10, 13, 100, 119, 18, 155, 6, 91, 40, 111, 11, 32, 55, 9, 10, 15, 37, 10, 115, 23, 124, 17
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7-3-5)=abs (-13) =13=a(6).
Abs (2-4-17-2)=abs(-21)=21=a(7).
Abs (3-2-19-2)=abs (-20)=20=a(8).
Abs (2-5-3-7)=abs (-13)=13=a(9).
Abs (2-11-23-2)=abs(-34)=34=a(10),
etc.
		

Crossrefs

Programs

  • Maple
    g:= proc(n) local F;
       F:= sort(ifactors(n)[2], (a,b) -> a[1]Robert Israel, Apr 25 2016
  • Mathematica
    Abs@ Total@ MapAt[Abs, Minus@ #, {1}] & /@ Partition[#, 4] &@ Flatten[FactorInteger /@ Range@ 134 /. {a_, b_} /; b == 1 :> {a}] (* Michael De Vlieger, Apr 25 2016 *)

Extensions

Corrected (10 replaced by 8) and extended by R. J. Mathar, Apr 18 2010

A123948 Triangle read by rows: first row is 1, and n-th row (n > 0) gives the coefficients in the expansion of the characteristic polynomial of the (n - 1)-th Bernstein basis matrix, horizontal flipped.

Original entry on oeis.org

1, 1, -1, -1, 1, 1, -2, 3, 3, -1, 9, -15, -22, 7, 1, 96, -184, -314, 139, 19, -1, -2500, 5250, 10575, -5375, -1026, 51, 1, -162000, 369900, 842310, -498171, -111179, 7644, 141, -1, 26471025, -64790985, -164634169, 109325076, 28870212, -2322404, -59193, 393, 1
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Oct 26 2006

Keywords

Comments

The Bernstein basis matrix of order n - 1 is an n X n matrix whose m-th row represents the coefficients in the expansion of the Bernstein basis polynomial defined as binomial(n, m)*x^m*(1 - x)^(n - m), 0 <= m <= n - 1. For n = 0, we obtain the 0 X 0 matrix. The convention is that the characteristic polynomial of the empty matrix is identically 1 (see [de Boor] and [Johnson et al.]). Row n of the present sequence is obtained by taking the characteristic polynomial of the matrix represented by the polynomials binomial(n, m)*x^(n - m)*(1 - x)^m. The resulting matrix is, in fact, the horizontal flipped version of the Bernstein basis matrix of order n (see example). - Franck Maminirina Ramaharo, Oct 19 2018

Examples

			Triangle begins:
        1;
        1,     -1;
       -1,      1,      1;
       -2,      3,      3,      -1;
        9,    -15,    -22,       7,       1;
       96,   -184,   -314,     139,      19,   -1;
    -2500,   5250,  10575,   -5375,   -1026,   51,   1;
  -162000, 369900, 842310, -498171, -111179, 7644, 141, -1;
      ...
From _Franck Maminirina Ramaharo_, Oct 19 2018: (Start)
Let n = 6 (i.e., order 5). The corresponding Bernstein basis matrix has the form
   1, -5,  10, -10,   5,  -1
   0,  5, -20,  30, -20,   5
   0,  0,  10, -30,  30, -10
   0,  0,   0,  10, -20,  10
   0,  0,   0,   0,   5,  -5
   0,  0,   0,   0,   0,   1.
Flipping this matrix horizontally gives the matrix for the polynomials binomial(5, m)*x^(5 - m)*(1 - x)^m, 0 <= m <= 5,
   0,  0,   0,   0,   0,   1
   0,  0,   0,   0,   5,  -5
   0,  0,   0,  10, -20,  10
   0,  0,  10, -30,  30, -10
   0,  5, -20,  30, -20,   5
   1, -5,  10, -10,   5,  -1
whose characteristic polynomial is -2500 + 5250*x + 10575*x^2 - 5375*x^3 - 1026*x^4 + 51*x^5 + x^6. (End)
		

References

  • Gengzhe Chang and Thomas W. Sederberg, Over and Over Again, The Mathematical Association of America, 1997, Chap. 30.

Crossrefs

Programs

  • Mathematica
    M[n_] := Table[CoefficientList[Binomial[n - 1, n - i - 1]*(1 - x)^i*x^(n - i - 1), x], {i, 0, n - 1}];
    Join[{1}, Table[CoefficientList[CharacteristicPolynomial[M[d], x], x], {d, 1, 10}]]//Flatten

Extensions

Edited, new name, offset corrected by Franck Maminirina Ramaharo, Oct 19 2018

A144022 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2+3-2, 2-5+2-3, 7-2+3-3, 2-2+5-11, 2-2+3-13, 2-7+3-5,..)).

Original entry on oeis.org

0, 4, 5, 6, 10, 7, 13, 18, 7, 12, 3, 11, 22, 27, 11, 17, 1, 51, 9, 35, 32, 4, 26, 4, 11, 40, 3, 5, 43, 56, 85, 6, 12, 57, 35, 67, 0, 105, 3, 21, 67, 2, 42, 1, 55, 19, 88, 9, 49, 59, 97, 6, 9, 102, 87, 12, 49, 0, 101, 36, 107, 35, 26, 63, 15, 6, 97, 27, 6, 129, 33, 128, 21, 62, 121
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7+3-5)=abs (-7) =7=a(6).
Abs (2-4+17-2)=abs(13)=13=a(7).
Abs (3-2+19-2)=abs (18)=18=a(8).
Abs (2-5+3-7)=abs (-7)=7=a(9).
Abs (2-11+23-2)=abs(12)=12=a(10),
etc.
		

Crossrefs

Extensions

Corrected (11 replaced by 9, 5 replaced by 6, 104 by 102) by R. J. Mathar, Apr 18 2010

A144076 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2*3-2, 2-5*2-3, 7-2*3-3, 2-2*5-11, 2-2*3-13, 2-7*3-5,..)).

Original entry on oeis.org

7, 11, 2, 19, 17, 24, 68, 37, 20, 253, 14, 40, 41, 44, 24, 90, 6, 4, 2, 28, 28, 9, 75, 13, 18, 77, 12, 2, 64, 52, 148, 13, 61, 736, 72, 104, 9, 4, 1, 60, 1026, 15, 3403, 24, 72, 12, 81, 88, 98, 252, 110, 15, 22, 199, 1750, 41, 206, 7, 88, 75, 222, 98, 87, 112, 8, 19, 64, 156
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7*3-5)=abs (-24) =24=a(6).
Abs (2-4*17-2)=abs(-68)=68=a(7).
Abs (3-2*19-2)=abs (-37)=37=a(8).
Abs (2-5*3-7)=abs (-20)=20=a(9).
Abs (2-11*23-2)=abs(-253)=253=a(10),
etc.
		

Crossrefs

Extensions

Corrected (12 replaced by 52) by R. J. Mathar, Apr 18 2010

A144114 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2^3-2, 2-5^2-3, 7-2^3-3, 2-2^5-11, 2-2^3-13, 2-7^3-5,..)).

Original entry on oeis.org

9, 26, 4, 41, 19, 346, 17179869184, 524287, 130, 895430243255237372246531, 242, 2198, 155, 272, 134, 1419862, 8, 524254, 0, 26, 28, 31, 2190, 48, 20, 8243, 30, 4, 387, 52, 3747, 127, 1220703121
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7^3-5)=abs (-346) =346=a(6).
Abs (2-4^17-2)=abs(-17179869184)=17179869184=a(7).
Abs (3-2^19-2)=abs (-524287)=524287=a(8).
Abs (2-5^3-7)=abs (-130)=130=a(9),
etc.
		

Crossrefs

Extensions

More terms from R. J. Mathar, Apr 18 2010

A173820 Coefficients of characteristic polynomials of Hadamard Cartan F_2 self-similar 2^n matrices:M={{2, -1}, {-2, 2}}.

Original entry on oeis.org

1, 2, -4, 1, 16, -64, 56, -16, 1, 4096, -32768, 75776, -77824, 39296, -9728, 1184, -64, 1, 4294967296, -68719476736, 375809638400, -1043677052928, 1696981843968, -1726845288448, 1143073669120, -506453819392, 152912134144, -31653363712
Offset: 0

Views

Author

Roger L. Bagula, Feb 25 2010

Keywords

Comments

Row sums are:
{1, -1, -7, -31, -208289151, 199276356275696712709633,
-27294457550222463310332530871924308277403810665846783,...}.

Examples

			{1},
{2, -4, 1},
{ 16, -64, 56, -16, 1},
{4096, -32768, 75776, -77824, 39296, -9728, 1184, -64, 1}, ...
		

Crossrefs

Programs

  • Mathematica
    Clear[HadamardMatrix];
    MatrixJoinH[A_, B_] := Transpose[Join[Transpose[A], Transpose[B]]]
    KroneckerProduct[M_, N_] := Module[{M1, N1, LM, LN, N2},
    M1 = M;
    N1 = N;
    LM = Length[M1];
    LN = Length[N1];
    Do[M1[[i, j]] = M1[[i, j]]N1, {i, 1, LM}, {j, 1, LM}];
    Do[M1[[i, 1]] = MatrixJoinH[M1[[i, 1]], M1[[i, j]]], {j, 2, LM}, {i, 1, LM}];
    N2 = {};
    Do[AppendTo[N2, M1[[i, 1]]], {i, 1, LM}];
    N2 = Flatten[N2];
    Partition[N2, LM*LN, LM*LN]]
    HadamardMatrix[2] := {{2, -1}, {-2, 2}}
    HadamardMatrix[n_] := Module[{m},
    m = {{2, -1}, {-2, 2}};
    KroneckerProduct[m, HadamardMatrix[n/2]]]
    Table[HadamardMatrix[2^n], {n, 1, 4}]
    Join[{{1}}, Table[CoefficientList[CharacteristicPolynomial[ HadamardMatrix[2^n], x], x], {n, 1, 6}]]
    Flatten[%]

Formula

M(2)={{2, -1}, {-2, 2}};
M(4)={{4, -2, -2, 1}, {-4, 4, 2, -2}, {-4, 2, 4, -2}, {4, -4, -4, 4}},etc.
Showing 1-7 of 7 results.