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 1-6 of 6 results.

A300656 Triangle read by rows: T(n,k) = 30*k^2*(n-k)^2 + 1; n >= 0, 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 1, 31, 1, 1, 121, 121, 1, 1, 271, 481, 271, 1, 1, 481, 1081, 1081, 481, 1, 1, 751, 1921, 2431, 1921, 751, 1, 1, 1081, 3001, 4321, 4321, 3001, 1081, 1, 1, 1471, 4321, 6751, 7681, 6751, 4321, 1471, 1, 1, 1921, 5881, 9721, 12001, 12001, 9721, 5881, 1921, 1
Offset: 0

Views

Author

Kolosov Petro, Mar 10 2018

Keywords

Comments

From Kolosov Petro, Apr 12 2020: (Start)
Let A(m, r) = A302971(m, r) / A304042(m, r).
Let L(m, n, k) = Sum_{r=0..m} A(m, r) * k^r * (n - k)^r.
Then T(n, k) = L(2, n, k).
Fifth power can be expressed as row sum of triangle T(n, k).
T(n, k) is symmetric: T(n, k) = T(n, n-k). (End)

Examples

			Triangle begins:
--------------------------------------------------------------------------
k=    0     1     2      3      4      5      6      7     8     9    10
--------------------------------------------------------------------------
n=0:  1;
n=1:  1,    1;
n=2:  1,   31,    1;
n=3:  1,  121,  121,     1;
n=4:  1,  271,  481,   271,     1;
n=5:  1,  481, 1081,  1081,   481,     1;
n=6:  1,  751, 1921,  2431,  1921,   751,     1;
n=7:  1, 1081, 3001,  4321,  4321,  3001,  1081,     1;
n=8:  1, 1471, 4321,  6751,  7681,  6751,  4321,  1471,    1;
n=9:  1, 1921, 5881,  9721, 12001, 12001,  9721,  5881, 1921,    1;
n=10: 1, 2431, 7681, 13231, 17281, 18751, 17281, 13231, 7681, 2431,   1;
		

Crossrefs

Various cases of L(m, n, k): A287326(m=1), This sequence (m=2), A300785(m=3). See comments for L(m, n, k).
Row sums give the nonzero terms of A002561.

Programs

  • GAP
    T:=Flat(List([0..9],n->List([0..n],k->30*k^2*(n-k)^2+1))); # Muniru A Asiru, Oct 24 2018
    
  • Magma
    [[30*k^2*(n-k)^2+1: k in [0..n]]: n in [0..12]]; // G. C. Greubel, Dec 14 2018
    
  • Maple
    a:=(n,k)->30*k^2*(n-k)^2+1: seq(seq(a(n,k),k=0..n),n=0..9); # Muniru A Asiru, Oct 24 2018
  • Mathematica
    T[n_, k_] := 30 k^2 (n - k)^2 + 1; Column[
    Table[T[n, k], {n, 0, 10}, {k, 0, n}], Center] (* Kolosov Petro, Apr 12 2020 *)
    f[n_]:=Table[SeriesCoefficient[(1 + 26 y + 336 y^2 + 326 y^3 + 31 y^4 + x^2 (1 + 116 y + 486 y^2 + 116 y^3 + y^4) + x (-2 - 82 y - 882 y^2 - 502 y^3 + 28 y^4))/((-1 + x)^3 (-1 + y)^5), {x, 0, i}, {y, 0, j}], {i, n, n}, {j, 0, n}]; Flatten[Array[f, 11, 0]] (* Stefano Spezia, Oct 30 2018 *)
  • PARI
    t(n, k) = 30*k^2*(n-k)^2+1
    trianglerows(n) = for(x=0, n-1, for(y=0, x, print1(t(x, y), ", ")); print(""))
    /* Print initial 9 rows of triangle as follows */ trianglerows(9)
    
  • Sage
    [[30*k^2*(n-k)^2+1 for k in range(n+1)] for n in range(12)] # G. C. Greubel, Dec 14 2018

Formula

From Kolosov Petro, Apr 12 2020: (Start)
T(n, k) = 30 * k^2 * (n-k)^2 + 1.
T(n, k) = 30 * A094053(n,k)^2 + 1.
T(n, k) = A158558((n-k) * k).
T(n+2, k) = 3*T(n+1, k) - 3*T(n, k) + T(n-1, k), for n >= k.
Sum_{k=1..n} T(n, k) = A000584(n).
Sum_{k=0..n-1} T(n, k) = A000584(n).
Sum_{k=0..n} T(n, k) = A002561(n).
Sum_{k=1..n-1} T(n, k) = A258807(n).
Sum_{k=1..n-1} T(n, k) = -A024003(n), n > 1.
Sum_{k=1..r} T(n, k) = A316349(2,r,0)*n^0 - A316349(2,r,1)*n^1 + A316349(2,r,2)*n^2. (End)
G.f.: (1 + 26*y + 336*y^2 + 326*y^3 + 31*y^4 + x^2*(1 + 116*y + 486*y^2 + 116*y^3 + y^4) + x*(-2 - 82*y - 882*y^2 - 502*y^3 + 28*y^4))/((-1 + x)^3*(-1 + y)^5). - Stefano Spezia, Oct 30 2018

A319214 a(n) = phi(n^5 - 1)/5 where phi is A000010.

Original entry on oeis.org

6, 22, 120, 280, 1240, 1120, 5400, 5280, 12960, 12880, 45240, 24752, 90240, 59160, 96000, 141984, 346880, 163800, 540000, 326720, 588984, 585120, 1523280, 582400, 1728000, 1203840, 2294712, 1758096, 4692408, 1388000, 6480000, 3787200, 5416800, 4783680, 7440000
Offset: 2

Views

Author

Seiichi Manyama, Sep 13 2018

Keywords

Crossrefs

Row 5 of A369291.
Cf. A000010, A258807 (n^5-1).
phi(n^b - 1)/b: A319210 (b=2), A319213 (b=3), this sequence (b=5).

Programs

  • Mathematica
    Table[EulerPhi[n^5-1]/5,{n,2,40}] (* Harvey P. Dale, Feb 09 2019 *)
  • PARI
    {a(n) = eulerphi(n^5-1)/5}

Formula

Sum_{k=1..n} a(k) = c * n^6 + O((n*log(n))^5), where c = (1/30) * Product_{p prime == 1 (mod 5)} (1 - 5/p^2) * Product_{p prime !== 1 (mod 5)} (1 - 1/p^2) = 0.019389107739... . - Amiram Eldar, Dec 09 2024

A258808 a(n) = n^7 - 1.

Original entry on oeis.org

0, 127, 2186, 16383, 78124, 279935, 823542, 2097151, 4782968, 9999999, 19487170, 35831807, 62748516, 105413503, 170859374, 268435455, 410338672, 612220031, 893871738, 1279999999, 1801088540, 2494357887, 3404825446, 4586471423, 6103515624, 8031810175
Offset: 1

Views

Author

Vincenzo Librandi, Jun 11 2015

Keywords

Crossrefs

Subsequence of A181126.
Cf. A258806.
Cf. similar sequences listed in A258807.

Programs

  • Magma
    [n^7-1: n in [1..40]];
    
  • Magma
    I:=[0,127,2186,16383, 78124,279935,823542,2097151]; [n le 8 select I[n] else 8*Self(n-1) - 28*Self(n-2)+56*Self(n-3)-70*Self(n-4)+56*Self(n-5) - 28*Self(n-6) +8*Self(n-7)-Self(n-8): n in [1..40]];
    
  • Mathematica
    Table[n^7 - 1, {n, 1, 40}] (* or *) LinearRecurrence[{8, -28, 56, -70, 56, -28, 8, -1}, {0, 127, 2186, 16383, 78124, 279935, 823542, 2097151}, 40]
  • Sage
    [n^7-1 for n in (1..40)] # Bruno Berselli, Jun 11 2015

Formula

G.f.: x^2*(127 + 1170*x + 2451*x^2 + 1156*x^3 + 141*x^4 - 6*x^5 + x^6)/(1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8).
a(n) = -A024005(n). [Bruno Berselli, Jun 11 2015]
a(n) = (n-1)*A053716(n). - Michel Marcus, Aug 21 2015

A258809 a(n) = n^8 - 1.

Original entry on oeis.org

0, 255, 6560, 65535, 390624, 1679615, 5764800, 16777215, 43046720, 99999999, 214358880, 429981695, 815730720, 1475789055, 2562890624, 4294967295, 6975757440, 11019960575, 16983563040, 25599999999, 37822859360, 54875873535, 78310985280, 110075314175
Offset: 1

Views

Author

Vincenzo Librandi, Jun 11 2015

Keywords

Crossrefs

Cf. similar sequences listed in A258807.

Programs

  • Magma
    [n^8-1: n in [1..40]];
  • Mathematica
    Table[n^8 - 1, {n, 33}] (* or *) LinearRecurrence[{9, -36, 84, -126, 126, -84, 36, -9, 1}, {0, 255, 6560, 65535, 390624, 1679615, 5764800, 16777215, 43046720}, 40]

Formula

G.f.: x^2*(225 + 4535*x + 14595*x^2 + 18069*x^3 + 569*x^4 + 3999*x^5 - 2511*x^6 + 1079*x^7 - 270*x^8 + 30*x^9) / (1 - x)^9.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9).
a(n) = (n - 1)*(n + 1)*(n^2 + 1)*(n^4 + 1) = -A024006(n). [Bruno Berselli, Jun 12 2015]

A258810 a(n) = n^9 - 1.

Original entry on oeis.org

0, 511, 19682, 262143, 1953124, 10077695, 40353606, 134217727, 387420488, 999999999, 2357947690, 5159780351, 10604499372, 20661046783, 38443359374, 68719476735, 118587876496, 198359290367, 322687697778, 511999999999, 794280046580, 1207269217791, 1801152661462
Offset: 1

Views

Author

Vincenzo Librandi, Jun 11 2015

Keywords

Crossrefs

Cf. A024007, similar sequences listed in A258807.

Programs

  • Magma
    [n^9-1: n in [1..40]];
    
  • Magma
    I:=[0,511,19682, 262143,1953124,10077695,40353606,134217727,387420488, 999999999]; [n le 10 select I[n] else 10*Self(n-1)-45*Self(n-2)+120*Self(n-3)-210*Self(n-4)+252*Self(n-5)-210*Self(n-6)+120*Self(n-7)-45*Self(n-8)+10*Self(n-9)-Self(n-10): n in [1..40]];
  • Mathematica
    Table[n^9 - 1, {n, 33}] (* or *) LinearRecurrence[{10, -45, 120, -210, 252, -210, 120, -45, 10, -1}, {0, 511, 19682, 262143, 1953124, 10077695, 40353606, 134217727, 387420488, 999999999}, 40]

Formula

G.f.: x^2*(511 + 14572*x + 88318*x^2 + 156064*x^3 + 88360*x^4 + 14524*x^5 + 538*x^6 - 8*x^7 + x^8)/(1-x)^10.
a(n) = 10*a(n-1)-45*a(n-2)+120*a(n-3)-210*a(n-4)+252*a(n-5)-210*a(n-6)+120*a(n-7)-45*a(n-8)+10*a(n-9)-a(n-10).

A258812 a(n) = n^11 - 1.

Original entry on oeis.org

0, 2047, 177146, 4194303, 48828124, 362797055, 1977326742, 8589934591, 31381059608, 99999999999, 285311670610, 743008370687, 1792160394036, 4049565169663, 8649755859374, 17592186044415, 34271896307632, 64268410079231, 116490258898218, 204799999999999
Offset: 1

Views

Author

Vincenzo Librandi, Jun 11 2015

Keywords

Crossrefs

Cf. A024009.
Cf. similar sequences listed in A258807.

Programs

  • Magma
    [n^11-1: n in [1..40]];
  • Mathematica
    Table[n^11 - 1, {n, 33}] (* or *) LinearRecurrence[{12, -66, 220, -495, 792, -924, 792, -495, 220, -66, 12, -1}, {0, 2047, 177146, 4194303, 48828124, 362797055, 1977326742, 8589934591, 31381059608, 99999999999, 285311670610, 743008370687}, 40]

Formula

G.f.: x^2* (2047 + 152582*x + 2203653*x^2 + 9737784*x^3 + 15724710*x^4 + 9737652*x^5 + 2203818*x^6 + 152472*x^7 + 2091*x^8 - 10*x^9 + x^10) / (1 - x)^12.
a(n) = 12*a(n-1) - 66*a(n-2) + 220*a(n-3) - 495*a(n-4) + 792*a(n-5) - 924*a(n-6) + 792*a(n-7) - 495*a(n-8) + 220*a(n-9) - 66*a(n-10) + 12*a(n-11) - a(n-12).
a(n) = -A024009(n). [Bruno Berselli, Jun 12 2015]
Showing 1-6 of 6 results.