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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A202750 Triangle T(n,k) = binomial(n,k)^4 read by rows, 0<=k<=n.

Original entry on oeis.org

1, 1, 1, 1, 16, 1, 1, 81, 81, 1, 1, 256, 1296, 256, 1, 1, 625, 10000, 10000, 625, 1, 1, 1296, 50625, 160000, 50625, 1296, 1, 1, 2401, 194481, 1500625, 1500625, 194481, 2401, 1, 1, 4096, 614656, 9834496, 24010000, 9834496, 614656, 4096, 1, 1, 6561, 1679616, 49787136, 252047376, 252047376, 49787136, 1679616, 6561, 1
Offset: 0

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Author

Keywords

Comments

Zhi-Wei Sun has conjectures related to the arithmetic mean of the polynomials formed from the rows of this sequence.

Examples

			Interpreted as polynomials:
1
x + 1
x^2 + 16*x + 1
x^3 + 81*x^2 + 81*x + 1
x^4 + 256*x^3 + 1296*x^2 + 256*x + 1
x^5 + 625*x^4 + 10000*x^3 + 10000*x^2 + 625*x + 1
		

Crossrefs

Cf. A007318.
Row sums give A005260.

Programs

  • PARI
    for(n=0,9,for(k=0,n,print1(binomial(n,k)^4", ")))

A216696 a(n) = Sum_{k=0..n} binomial(n,k)^4 * 2^k.

Original entry on oeis.org

1, 3, 37, 495, 7761, 131283, 2336629, 43174911, 819869185, 15906350403, 313905320037, 6281740700271, 127173173346129, 2599950664710675, 53601450936173877, 1113117091905581055, 23262762639358582785, 488890438209132473475, 10325711607889973605285, 219057502101780979753455
Offset: 0

Views

Author

Vaclav Kotesovec, Sep 15 2012

Keywords

Crossrefs

Cf. A005260.

Programs

  • Mathematica
    Table[Sum[Binomial[n, k]^4*2^k, {k, 0, n}], {n, 0, 25}]

Formula

Recurrence: (864*n^8 + 14256*n^7 + 99843*n^6 + 386844*n^5 + 905129*n^4 + 1307419*n^3 + 1137462*n^2 + 545141*n + 110362)*a(n) - (673920*n^8 + 12130560*n^7 + 94006260*n^6 + 409620480*n^5 + 1097677875*n^4 + 1852470090*n^3 + 1922754750*n^2 + 1122222315*n + 281983230)*a(n+1) - (188352*n^8 + 3672864*n^7 + 30977310*n^6 + 147448176*n^5 + 432716089*n^4 + 800645440*n^3 + 910682766*n^2 + 581183533*n + 159056590)*a(n+2) - (10368*n^8 + 217728*n^7 + 1969236*n^6 + 10003440*n^5 + 31163253*n^4 + 60851106*n^3 + 72587550*n^2 + 48264909*n + 13672710)*a(n+3) + (864*n^8 + 19440*n^7 + 187539*n^6 + 1011492*n^5 + 3330104*n^4 + 6840009*n^3 + 8542572*n^2 + 5919152*n + 1739328)*a(n+4) = 0.
a(n) ~ (1+2^(1/4))^3/(4*2^(7/8)*Pi^(3/2)) * (1+2^(1/4))^(4*n)/n^(3/2). - Vaclav Kotesovec, Sep 19 2012
Generally, Sum_{k=0..n} binomial(n,k)^p*x^k is asymptotic a(n) ~ (1+x^(1/p))^(p*n+p-1)/sqrt((2*pi*n)^(p-1)*p*x^(1-1/p)). This is case p=4, x=2. - Vaclav Kotesovec, Sep 19 2012

Extensions

Minor edits by Vaclav Kotesovec, Mar 31 2014

A096192 a(n) = Sum_{k=1..n} C(n,k)^4 where C(n,k) is binomial(n,k).

Original entry on oeis.org

1, 17, 163, 1809, 21251, 263843, 3395015, 44916497, 607041379, 8345319267, 116335834055, 1640651321763, 23365271704711, 335556407724359, 4854133484555663, 70666388112940817, 1034529673001901731
Offset: 1

Views

Author

Gerald McGarvey, Jul 25 2004

Keywords

Crossrefs

Equals A005260(n) - 1.

Programs

  • Mathematica
    Table[Sum[Binomial[n, k-1]^4, {k, 0, n}], {n, 1, 25}] (* Vincenzo Librandi, May 03 2013 *)

Formula

a(n) ~ 2^(4*n + 1/2) / (Pi*n)^(3/2). - Vaclav Kotesovec, Nov 27 2017

A172434 G.f.: Sum_{n>=0} a(n)*x^n/n!^4 = [ Sum_{n>=0} x^n/n!^4 ]^3.

Original entry on oeis.org

1, 3, 51, 1785, 67635, 2973753, 146591529, 7735733883, 430208938035, 24954576411225, 1496639801457801, 92241539987122683, 5816057121183700521, 373854785336483200155, 24431647104881328618315, 1619654401178752389082785
Offset: 0

Views

Author

Paul D. Hanna, Jan 20 2011

Keywords

Examples

			G.f.: A(x) = 1 + 3*x + 51*x^2/2!^4 + 1785*x^3/3!^4 + 67635*x^4/4!^4 +...
A(x)^(1/3) = 1 + x + x^2/2!^4 + x^3/3!^4 + x^4/4!^4 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=if(n<0, 0, n!^4*polcoeff(sum(m=0, n, x^m/m!^4+x*O(x^n))^3, n))}
    
  • PARI
    {a(n)=sum(k=0, n, binomial(n, k)^4*sum(j=0, k, binomial(k, j)^4))}

Formula

a(n) = Sum_{k=0..n} C(n,k)^4 * Sum_{j=0..k} C(k,j)^4 = Sum_{k=0..n} C(n,k)^4 * A005260(k).

A178824 a(n) = Sum_{k=0..n} binomial(n,k)^4/(n+1).

Original entry on oeis.org

1, 1, 6, 41, 362, 3542, 37692, 424377, 4990722, 60704138, 758665388, 9694652838, 126203947828, 1668947978908, 22370427181624, 303383342784729, 4156846359584754, 57473870722327874, 801081711581734764, 11246487794657694810, 158920231643036635860, 2258896576436091238860
Offset: 0

Views

Author

Paul D. Hanna, Dec 27 2010

Keywords

Crossrefs

Programs

  • GAP
    List([0..20], n-> Sum([0..n], k-> Binomial(n,k)^4/(n+1) )); # G. C. Greubel, Jan 22 2019
  • Magma
    [(&+[Binomial(n,k)^4/(n+1): k in [0..n]]): n in [0..20]]; // G. C. Greubel, Jan 22 2019
    
  • Maple
    a:=n->add(binomial(n,k)^4/(n+1),k=0..n): seq(a(n),n=0..20); # Muniru A Asiru, Jan 22 2019
  • Mathematica
    Table[Sum[Binomial[n,k]^4/(n+1), {k,0,n}], {n,0,20}] (* G. C. Greubel, Jan 22 2019 *)
  • PARI
    {a(n)=sum(k=0, n, binomial(n, k)^4)/(n+1)}
    
  • Sage
    [sum(binomial(n,k)^4/(n+1) for k in (0..n)) for n in (0..20)] # G. C. Greubel, Jan 22 2019
    

Formula

a(n) = A005260(n)/(n+1).
a(n) = Sum_{k=0..n} binomial(n,k)^2 * ( binomial(n,k) - binomial(n,k-1) )^2. - Seiichi Manyama, Mar 26 2025
a(n) ~ 2^(4*n + 1/2) / (Pi^(3/2) * n^(5/2)). - Vaclav Kotesovec, Mar 26 2025

A249332 a(n) = Sum_{k=0..2*n} binomial(2*n, k)^4.

Original entry on oeis.org

1, 18, 1810, 263844, 44916498, 8345319268, 1640651321764, 335556407724360, 70666388112940818, 15220552520052960516, 3337324864503769353060, 742446552655157791828680, 167167472732516775004539300, 38021985442071415426063237704, 8723111727436784830252513497928
Offset: 0

Views

Author

Michael Somos, Oct 25 2014

Keywords

Crossrefs

Programs

  • Magma
    [(&+[Binomial(2*n,k)^4: k in [0..2*n]]): n in [0..30]]; // G. C. Greubel, Aug 04 2018
  • Mathematica
    Table[Sum[Binomial[2*n, k]^4, {k, 0, 2*n}], {n, 0, 30}] (* G. C. Greubel, Aug 04 2018 *)
  • PARI
    {a(n) = sum(k=0, 2*n, binomial( 2*n, k)^4)};
    

Formula

a(n) = A005260(2*n).

A262705 Triangle: Newton expansion of C(n,m)^4, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 14, 1, 0, 36, 78, 1, 0, 24, 978, 252, 1, 0, 0, 4320, 8730, 620, 1, 0, 0, 8460, 103820, 46890, 1290, 1, 0, 0, 7560, 581700, 1159340, 185430, 2394, 1, 0, 0, 2520, 1767360, 13387570, 8314880, 595476, 4088, 1, 0, 0, 0, 3087000, 85806000, 170429490, 44341584, 1642788, 6552, 1
Offset: 0

Views

Author

Giuliano Cabrele, Sep 30 2015

Keywords

Comments

Triangle here T_4(n,m) is such that C(n,m)^4 = Sum_{j=0..n} C(n,j)*T_4(j,m).
Equivalently, lower triangular matrix T_4 such that
|| C(n,m)^4 || = A202750 = P * T_4 = A007318 * T_4.
T_4(n,m) = 0 for n < m and for 4*m < n.
Refer to comment to A262704.
Example:
C(x,2)^4 = x^4*(x-1)^4 /16 = 1*C(x,2) + 78*C(x,3) + 978*C(x,4) + 4320*C(x,5) + 8460*C(x,6) + 7560*C(x,7) + 2520*C(x,8);
C(5,2)^4 = C(5,3)^4 = 10000 = 1*C(5,2) + 78*C(5,3) + 978*C(5,4) + 4320*C(5,5) = 1*C(5,3) + 252*C(5,4) + 8730*C(5,5).

Examples

			Triangle starts:
[1];
[0,  1];
[0, 14,    1];
[0, 36,   78,      1];
[0, 24,  978,    252,     1];
[0,  0, 4320,   8730,   620,    1];
[0,  0, 8460, 103820, 46890, 1290, 1];
		

Crossrefs

Row sums are, by definition, the inverse binomial transform of A005260.
Second diagonal (T_4(n+1,n)) is A058895(n+1).
Column T_4(n,2) is A122193(4,n).
Cf. A109983 (transpose of), A262704, A262706.

Programs

  • Magma
    [&+[(-1)^(n-j)*Binomial(n,j)*Binomial(j,m)^4: j in [0..n]]: m in [0..n], n in [0..10]]; // Bruno Berselli, Oct 01 2015
    
  • Mathematica
    T4[n_, m_] := Sum[(-1)^(n - j) * Binomial[n, j] * Binomial[j, m]^4, {j, 0, n}]; Table[T4[n, m], {n, 0, 9}, {m, 0, n}] // Flatten (* Jean-François Alcover, Oct 01 2015 *)
  • MuPAD
    // as a function
    T_4:=(n,m)->_plus((-1)^(n-j)*binomial(n,j)*binomial(j,m)^4 $ j=0..n):
    // as a matrix h x h
    _P:=h->matrix([[binomial(n,m) $m=0..h]$n=0..h]):
    _P_4:=h->matrix([[binomial(n,m)^4 $m=0..h]$n=0..h]):
    _T_4:=h->_P(h)^-1*_P_4(h):
    
  • PARI
    T_4(nmax) = {for(n=0, nmax, for(m=0, n, print1(sum(j=0, n, (-1)^(n-j)*binomial(n,j)*binomial(j,m)^4), ", ")); print())} \\ Colin Barker, Oct 01 2015

Formula

T_4(n,m) = Sum_{j=0..n} (-1)^(n-j)*C(n,j)*C(j,m)^4.
Also, let S(r,s)(n,m) denote the Generalized Stirling2 numbers as defined in the link above, then T_4(n,m) = n! / (m!)^4 * S(m,m)(4,n).

A274786 Diagonal of the rational function 1/(1 - (wxz + wy + wz + xy + xz + y + z)).

Original entry on oeis.org

1, 6, 114, 2940, 87570, 2835756, 96982116, 3446781624, 126047377170, 4712189770860, 179275447715364, 6918537571788024, 270178056420497316, 10656693484898995800, 423937118582497715400, 16989669600664370275440, 685277433339552643145490, 27797911234749454227812460, 1133299570662800455270517700
Offset: 0

Views

Author

Gheorghe Coserea, Jul 14 2016

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Sum[(-1)^j Binomial[2n, j] Binomial[j, n]^3, {j, n, 2n}];
    (* or much faster *)
    a[0] = 1; a[1] = 6; a[n_] := a[n] = (2*(2*n - 1)*(11*n^2 - 11*n + 3)*a[n - 1] + 4*(n - 1)*(2*n - 3)*(2*n - 1)*a[n - 2])/n^3;
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Dec 01 2017, after Vaclav Kotesovec *)
  • PARI
    a(n) = sum(j=n, 2*n, (-1)^(j)*binomial(2*n, 2*n - j)*binomial(j, n)^3);
    
  • PARI
    my(x='x, y='y, z='z, w='w);
    R = 1/(1-(w*x*z+w*y+w*z+x*y+x*z+y+z));
    diag(n, expr, var) = {
      my(a = vector(n));
      for (i = 1, #var, expr = taylor(expr, var[#var - i + 1], n));
      for (k = 1, n, a[k] = expr;
           for (i = 1, #var, a[k] = polcoeff(a[k], k-1)));
      return(a);
    };
    diag(18, R, [x,y,z,w])

Formula

a(n) = Sum_{j=0..2*n} (-1)^j * binomial(2*n,j) * binomial(j,n)^3.
a(n) = T(2*n,n), where triangle T(n,k) is defined by A262704.
0 = (-x^2+44*x^3+16*x^4)*y''' + (-3*x+198*x^2+96*x^3)*y'' + (-1+144*x+108*x^2)*y' + (6+12*x)*y, where y is the g.f.
Recurrence: n^3*a(n) = 2*(2*n - 1)*(11*n^2 - 11*n + 3)*a(n-1) + 4*(n-1)*(2*n - 3)*(2*n - 1)*a(n-2). - Vaclav Kotesovec, Dec 01 2017
a(n) ~ 2^(2*n - 1) * phi^(5*n + 5/2) / (5^(1/4) * (Pi*n)^(3/2)), where phi = A001622 = (1 + sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Dec 01 2017
Conjecture: a(n) = [x^n] (1 + x)^(2*n) * P(n,(1 + x)/(1 - x))^2, where P(n,x) denotes the n-th Legendre polynomial. Cf. A005260(n) = [x^n] (1 - x)^(2*n) * P(n,(1 + x)/(1 - x))^2, due to Carlitz. - Peter Bala, Sep 21 2021
a(n) = A000984(n) * A005258(n). - Peter Bala, Oct 12 2024

A328735 Constant term in the expansion of (x + y + z + 1/x + 1/y + 1/z + x*y + y*z + z*x + 1/(x*y) + 1/(y*z) + 1/(z*x) + x*y*z + 1/(x*y*z))^n.

Original entry on oeis.org

1, 0, 14, 72, 882, 8400, 95180, 1060080, 12389650, 146472480, 1767391164, 21581516880, 266718438756, 3327025429728, 41849031952728, 530135326392672, 6757845419895570, 86619827323917888, 1115719258312182524, 14434274832755201424, 187477238295444829732
Offset: 0

Views

Author

Seiichi Manyama, Oct 26 2019

Keywords

Crossrefs

Column k=4 of A328748.
Sum_{i=0..n} (-2)^(n-i)*binomial(n,i)*Sum_{j=0..i} binomial(i,j)^m: A126869 (m=2), A002898 (m=3), this sequence (m=4), A328751 (m=5).

Programs

  • Mathematica
    Table[Sum[(-2)^(n-i)*Binomial[n,i] * Sum[Binomial[i,j]^4, {j,0,i}], {i,0,n}], {n,0,20}] (* Vaclav Kotesovec, Mar 20 2023 *)
  • PARI
    {a(n) = polcoef(polcoef(polcoef((-2+(1+x)*(1+y)*(1+z)+(1+1/x)*(1+1/y)*(1+1/z))^n, 0), 0), 0)}
    
  • PARI
    {a(n) = sum(i=0, n, (-2)^(n-i)*binomial(n, i)*sum(j=0, i, binomial(i, j)^4))}

Formula

a(n) = Sum_{i=0..n} (-2)^(n-i)*binomial(n,i)*Sum_{j=0..i} binomial(i,j)^4.
From Vaclav Kotesovec, Mar 20 2023: (Start)
Recurrence: n^3*a(n) = 2*(n-1)*n*(2*n - 1)*a(n-1) + 112*(n-1)^3*a(n-2) + 184*(n-2)*(n-1)*(2*n - 3)*a(n-3) + 336*(n-3)*(n-2)*(n-1)*a(n-4).
a(n) ~ 2^(n-4) * 7^(n + 3/2) / (Pi^(3/2) * n^(3/2)). (End)

A382841 a(n) = Sum_{k=0..floor(n/2)} (binomial(n,k) * binomial(n-k,k))^2.

Original entry on oeis.org

1, 1, 5, 37, 181, 1301, 9401, 65465, 498037, 3796021, 29221705, 230396585, 1828448425, 14651160265, 118544522045, 965075143037, 7907605360757, 65162569952245, 539515760866889, 4486877961224297, 37463151704756281, 313909383754331801, 2638892573249746445, 22249830926517611917
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 06 2025

Keywords

Comments

Diagonal of the rational function 1 / ((1 - x)*(1 - y)*(1 - z)*(1 - w) - (x*y)^2*z*w).

Crossrefs

Programs

  • Maple
    a:= n-> add(combinat[multinomial](n, n-2*k, k$2)^2, k=0..n/2):
    seq(a(n), n=0..23);  # Alois P. Heinz, Apr 07 2025
  • Mathematica
    Table[Sum[(Binomial[n, k] Binomial[n - k, k])^2, {k, 0, Floor[n/2]}], {n, 0, 23}]
    Table[HypergeometricPFQ[{1/2 - n/2, 1/2 - n/2, -n/2, -n/2}, {1, 1, 1}, 16], {n, 0, 23}]
    Table[SeriesCoefficient[1/((1 - x) (1 - y) (1 - z) (1 - w) - (x y)^2 z w), {x, 0, n}, {y, 0, n}, {z, 0, n}, {w, 0, n}], {n, 0, 23}]

Formula

a(n) ~ 3^(2*n+2) / (2^(5/2) * Pi^(3/2) * n^(3/2)). - Vaclav Kotesovec, Apr 07 2025
a(n) = Sum_{k=0..floor(n/2)} A089627(n,k)^2. - Alois P. Heinz, Apr 07 2025
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