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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A112461 Absolute value of coefficient of term [x^(n-5)] in characteristic polynomial of maximum matrix A of size n X n, where n >= 5. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n.

Original entry on oeis.org

5, 59, 374, 1694, 6149, 19019, 52052, 129272, 296582, 636922, 1293292, 2502604, 4644094, 8306914, 14382544, 24188824, 39633715, 63428365, 99360690, 152642490, 230345115, 341940885, 499969860, 720854160, 1025884860, 1442409540, 2005251864, 2758398104
Offset: 5

Views

Author

Paul Max Payton, Sep 23 2005

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(9n+5)/10! Product[n+i,{i,-4,4}],{n,5,40}] (* Harvey P. Dale, Apr 26 2019 *)

Formula

a(n) = ((9n+5)/10!) * Product_{i=-4..4} (n+i).
G.f.: x^5*(5+4*x)/(1-x)^11. - Colin Barker, Mar 28 2012

Extensions

Offset changed from 1 to 5, formulas and b-file adapted by Bruno Berselli, Mar 29 2012

A112462 Absolute value of coefficient of term [x^(n-6)] in characteristic polynomial of maximum matrix A of size n X n, where n >= 6. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n.

Original entry on oeis.org

6, 83, 611, 3185, 13195, 46228, 142324, 395148, 1007760, 2393430, 5349526, 11345698, 22985326, 44722580, 83947700, 152591660, 269449830, 463484385, 778439025, 1279189275, 2060359665, 3257868120, 5064210840, 7748481000, 11682325200, 17373286476, 25507265868
Offset: 6

Views

Author

Paul Max Payton, Sep 23 2005

Keywords

Crossrefs

Formula

a(n) = ((11n+6)/12!) * Product_{i=-5..5} (n+i).
G.f.: x^6*(6+5*x)/(1-x)^13. - Colin Barker, Mar 28 2012

Extensions

Offset changed from 1 to 6, formulas and b-file adapted by Bruno Berselli, Mar 29 2012

A112464 Absolute value of coefficient of term [x^(n-8)] in characteristic polynomial of maximum matrix A of size n X n, where n >= 8. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n.

Original entry on oeis.org

8, 143, 1343, 8823, 45543, 196707, 739347, 2483547, 7599867, 21492097, 56794705, 141485305, 334639305, 755863605, 1638428805, 3422280285, 6912424485, 13541987610, 25799313210, 47907161610, 86882479530, 154161302130, 268050218130, 457369908930, 766795640130
Offset: 8

Views

Author

Paul Max Payton, Sep 23 2005

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(Times@@(n+Range[0,14])(15n+113))/16!,{n,30}] (* or *) CoefficientList[ Series[ (-8-7 x)/(-1+x)^17,{x,0,30}],x] (* Harvey P. Dale, Jul 24 2011 *)

Formula

a(n) = ((15n+8)/16!) * Product_{i=-7..7} (n+i).
G.f.: x^8*(8+7*x)/(1-x)^17. - Harvey P. Dale, Jul 24 2011

Extensions

More terms from Harvey P. Dale, Jul 24 2011
Offset changed from 0 to 8, formulas and b-file adapted by Bruno Berselli, Mar 29 2012

A259749 Numbers that are congruent to {1,2,5,7,10,11,13,17,19,23} mod 24.

Original entry on oeis.org

1, 2, 5, 7, 10, 11, 13, 17, 19, 23, 25, 26, 29, 31, 34, 35, 37, 41, 43, 47, 49, 50, 53, 55, 58, 59, 61, 65, 67, 71, 73, 74, 77, 79, 82, 83, 85, 89, 91, 95, 97, 98, 101, 103, 106, 107, 109, 113, 115, 119, 121, 122, 125, 127, 130, 131, 133, 137, 139, 143, 145
Offset: 1

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Author

Keywords

Comments

Original name: Numbers n such that A259748(n) = 0.

Crossrefs

Cf. A000914.
Other sequences of numbers n such that A259748(n)/n equals a constant: A008606, A073762, A259750, A259751, A259752, A259754, A259755.

Programs

  • Mathematica
    A[n_] := A[n] = Sum[a b, {a, 1, n}, {b, a + 1, n}] ; Select[Range[600], Mod[A[#], #]  == 0 & ]
    Rest@ CoefficientList[Series[x (1 + x^2) (1 + 2 x^2 - x^3 + 2 x^4 - 2 x^5 + 3 x^6 + x^7)/((1 - x)^2*(1 - x + x^2 - x^3 + x^4) (1 + x + x^2 + x^3 + x^4)), {x, 0, 61}], x] (* Michael De Vlieger, Aug 25 2016 *)
    Select[Range[150],MemberQ[{1,2,5,7,10,11,13,17,19,23},Mod[#,24]]&] (* or *) LinearRecurrence[{2,-2,2,-2,2,-2,2,-2,2,-1},{1,2,5,7,10,11,13,17,19,23},70] (* Harvey P. Dale, Jan 15 2022 *)
  • PARI
    Vec(x*(1+x^2)*(1+2*x^2-x^3+2*x^4-2*x^5+3*x^6+x^7)/((1-x)^2*(1-x+x^2-x^3+x^4)*(1+x+x^2+x^3+x^4)) + O(x^100)) \\ Colin Barker, Aug 25 2016

Formula

A259748(a(n)) = Sum_{x*y: x,y in Z/a(n)Z, x<>y} = 0.
G.f.: x*(1+x^2)*(1+2*x^2-x^3+2*x^4-2*x^5+3*x^6+x^7) / ((1-x)^2*(1-x+x^2-x^3+x^4)*(1+x+x^2+x^3+x^4)). - Colin Barker, Aug 25 2016

Extensions

Better name from Danny Rorabaugh, Oct 22 2015

A259751 Numbers that are congruent to {8, 16} mod 24.

Original entry on oeis.org

8, 16, 32, 40, 56, 64, 80, 88, 104, 112, 128, 136, 152, 160, 176, 184, 200, 208, 224, 232, 248, 256, 272, 280, 296, 304, 320, 328, 344, 352, 368, 376, 392, 400, 416, 424, 440, 448, 464, 472, 488, 496, 512, 520, 536, 544, 560, 568, 584, 592, 608, 616, 632
Offset: 1

Views

Author

Keywords

Comments

Original name: Numbers n such that n/A259748(n) = 4.

Crossrefs

Other sequences of numbers n such that A259748(n)/n equals a constant: A008606, A073762, A259749, A259750, A259752, A259754, A259755.

Programs

  • Mathematica
    A[n_] := A[n] = Sum[a b, {a, 1,  n}, {b, a + 1, n}] ; Select[Range[600], Mod[A[#], #]/# == 1/4 & ]
  • PARI
    Vec(8*x*(1+x+x^2)/((1-x)^2*(1+x)) + O(x^100)) \\ Colin Barker, Aug 26 2016

Formula

A259748(a(n))/a(n) = 1/4.
a(n) = 8*A001651. - Danny Rorabaugh, Oct 22 2015
From Colin Barker, Aug 26 2016: (Start)
a(n) = 12*n-2*(-1)^n-6.
a(n) = a(n-1)+a(n-2)-a(n-3) for n>3.
G.f.: 8*x*(1+x+x^2) / ((1-x)^2*(1+x)).
(End)
Sum_{n>=1} (-1)^(n+1)/a(n) = sqrt(3)*Pi/72. - Amiram Eldar, Dec 31 2021
E.g.f.: 2*(4 + (6*x - 3)*exp(x) - exp(-x)). - David Lovler, Sep 05 2022

Extensions

Better name from Danny Rorabaugh, Oct 22 2015

A259752 a(n) = 24*n - 18.

Original entry on oeis.org

6, 30, 54, 78, 102, 126, 150, 174, 198, 222, 246, 270, 294, 318, 342, 366, 390, 414, 438, 462, 486, 510, 534, 558, 582, 606, 630, 654, 678, 702, 726, 750, 774, 798, 822, 846, 870, 894, 918, 942, 966, 990, 1014, 1038, 1062, 1086, 1110, 1134, 1158, 1182, 1206
Offset: 1

Views

Author

Keywords

Comments

Original name: Numbers n such that n/A259748(n) = 6.
Partial sums give A152746. - Leo Tavares, Jul 29 2023

Crossrefs

Other sequences of numbers n such that A259748(n)/n equals a constant: A008606, A073762, A259749, A259750, A259751, A259754, A259755.

Programs

  • Mathematica
    A[n_] := A[n] = Sum[a b, {a, 1,  n}, {b, a + 1, n}] ; Select[Range[600], Mod[A[#], #]/# == 1/6 & ]

Formula

A259748(a(n))/a(n) = 1/6.
a(n) = 6*A016813(n-1). - Michel Marcus, Jul 18 2015
G.f.: 6*x*(3*x+1)/(x-1)^2. - Alois P. Heinz, Jul 29 2023
From Elmo R. Oliveira, Apr 04 2025: (Start)
E.g.f.: 6*(exp(x)*(4*x - 3) + 3).
a(n) = 2*a(n-1) - a(n-2) for n > 2. (End)

Extensions

Better name from Danny Rorabaugh, Oct 22 2015

A259754 Numbers that are congruent to {3,9,15,18,21} mod 24.

Original entry on oeis.org

3, 9, 15, 18, 21, 27, 33, 39, 42, 45, 51, 57, 63, 66, 69, 75, 81, 87, 90, 93, 99, 105, 111, 114, 117, 123, 129, 135, 138, 141, 147, 153, 159, 162, 165, 171, 177, 183, 186, 189, 195, 201, 207, 210, 213, 219, 225, 231, 234, 237, 243, 249, 255, 258, 261, 267
Offset: 1

Views

Author

Keywords

Comments

Original name: Numbers n such that n/A259748(n) = 3/2.

Crossrefs

Cf. A000914.
Other sequences of numbers n such that A259748(n)/n equals a constant: A008606, A073762, A259749, A259750, A259751, A259752, A259755.

Programs

  • Mathematica
    A[n_] := A[n] = Sum[a b, {a, 1, n}, {b, a + 1, n}]; Select[Range[200], Mod[A[#], #]/# == 2/3 &]
    Rest@ CoefficientList[Series[3 x (1 + x) (1 + x + x^2 + x^4)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)), {x, 0, 56}], x] (* Michael De Vlieger, Aug 25 2016 *)
    LinearRecurrence[{1,0,0,0,1,-1},{3,9,15,18,21,27},60] (* Harvey P. Dale, Aug 30 2016 *)
  • PARI
    Vec(3*x*(1+x)*(1+x+x^2+x^4)/((1-x)^2*(1+x+x^2+x^3+x^4)) + O(x^100)) \\ Colin Barker, Aug 25 2016

Formula

A259748(a(n))/a(n) = 2/3.
a(n) = 3*A047584(n). - Michel Marcus, Jul 18 2015
From Colin Barker, Aug 25 2016: (Start)
a(n) = a(n-1)+a(n-5)-a(n-6) for n>6.
G.f.: 3*x*(1+x)*(1+x+x^2+x^4) / ((1-x)^2*(1+x+x^2+x^3+x^4)).
(End)

Extensions

Better name from Danny Rorabaugh, Oct 22 2015

A112459 Absolute value of coefficient of term [x^(n-3)] in characteristic polynomial of maximum matrix A of size n X n, where n >= 3. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n.

Original entry on oeis.org

3, 23, 98, 308, 798, 1806, 3696, 6996, 12441, 21021, 34034, 53144, 80444, 118524, 170544, 240312, 332367, 452067
Offset: 3

Views

Author

Paul Max Payton, Sep 23 2005

Keywords

Crossrefs

Formula

a(n) = n*(n^2-4)*(n^2-1)*(5*n+3)/6!.
G.f.: x^3*(3+2*x)/(1-x)^7. - Colin Barker, Mar 28 2012

Extensions

Offset changed from 1 to 3 and formulas adapted by Bruno Berselli, Mar 29 2012

A112460 Absolute value of coefficient of term [x^(n-4)] in characteristic polynomial of maximum matrix A of size n X n, where n >= 4. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n.

Original entry on oeis.org

4, 39, 207, 795, 2475, 6633, 15873, 34749, 70785, 135850, 247962, 433602, 730626, 1191870, 1889550, 2920566, 4412826, 6532713, 9493825, 13567125, 19092645, 26492895, 36288135, 49113675, 65739375, 87091524, 114277284, 148611892, 191648820, 245213100, 311438028
Offset: 4

Views

Author

Paul Max Payton, Sep 23 2005

Keywords

Crossrefs

Programs

  • Mathematica
    Drop[Table[(7n^8+4n^7-98n^6-56n^5+343n^4+196n^3-252n^2-144n)/40320,{n,40}],3] (* Harvey P. Dale, Dec 15 2013 *)

Formula

a(n) = (n-3)*(n-2)*(n-1)*n*(n+1)*(n+2)*(n+3)*(7*n+4)/8!.
G.f.: x^4*(4+3*x)/(1-x)^9. - Colin Barker, Mar 28 2012

A112463 Absolute value of coefficient of term [x^(n-7)] in characteristic polynomial of maximum matrix A of size n X n, where n >= 7. Maximum matrix A(i,j) is MAX(i,j), where indices i and j run from 1 to n.

Original entry on oeis.org

7, 111, 930, 5480, 25500, 99756, 341088, 1046520, 2936070, 7638950, 18631932, 42969336, 94348300, 198354300, 401166000, 783610920, 1483311285, 2728813725, 4891144350, 8560278000, 14656684680, 24591569640, 40493836800, 65527390800, 104329399500, 163608855372
Offset: 7

Views

Author

Paul Max Payton, Sep 23 2005

Keywords

Crossrefs

Formula

a(n) = ((13*n+7)/14!) * Product_{i=-6..6} (n+i).
G.f.: x^7*(7+6*x)/(1-x)^15. - Colin Barker, Mar 28 2012

Extensions

Offset changed by Alois P. Heinz, Mar 28 2012
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