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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A027969 a(n) = T(n, 2*n-7), T given by A027960.

Original entry on oeis.org

3, 7, 18, 47, 120, 291, 661, 1404, 2801, 5283, 9484, 16305, 26990, 43215, 67191, 101782, 150639, 218351, 310614, 434419, 598260, 812363, 1088937, 1442448, 1889917, 2451243, 3149552, 4011573, 5068042, 6354135, 7909931, 9780906, 12018459, 14680471, 17831898, 21545399, 25902000, 30991795
Offset: 4

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Author

Keywords

Crossrefs

A column of triangle A027011.

Programs

  • GAP
    List([4..50], n-> (90720 -85548*n +38822*n^2 -10136*n^3 +1505*n^4 -77*n^5 -7*n^6 + n^7)/5040) # G. C. Greubel, Jul 01 2019
  • Magma
    [(90720 -85548*n +38822*n^2 -10136*n^3 +1505*n^4 -77*n^5 -7*n^6 + n^7)/5040: n in [4..50]]; // G. C. Greubel, Jul 01 2019
    
  • Mathematica
    Table[(90720 -85548*n +38822*n^2 -10136*n^3 +1505*n^4 -77*n^5 -7*n^6 + n^7)/5040, {n,4,50}] (* G. C. Greubel, Jul 01 2019 *)
  • PARI
    for(n=4,50, print1((90720 -85548*n +38822*n^2 -10136*n^3 +1505*n^4 -77*n^5 -7*n^6 + n^7)/5040, ", ")) \\ G. C. Greubel, Jul 01 2019
    
  • Sage
    [(90720 -85548*n +38822*n^2 -10136*n^3 +1505*n^4 -77*n^5 -7*n^6 + n^7)/5040 for n in (4..50)] # G. C. Greubel, Jul 01 2019
    

Formula

From Ralf Stephan, Feb 07 2004: (Start)
G.f.: x^4*(3-2x)*(1-x+x^2)*(1-4x+7x^2-4x^3+x^4)/(1-x)^8.
First differences of A027970. (End)
From G. C. Greubel, Jul 01 2019: (Start)
a(n) = (90720 -85548*n +38822*n^2 -10136*n^3 +1505*n^4 -77*n^5 -7*n^6 + n^7)/5040.
E.g.f.: (-90720 - 35280*x - 7560*x^2 - 1680*x^3 + (90720 - 55440*x + 17640*x^2 - 3360*x^3 + 630*x^4 - 42*x^5 + 14*x^6 + x^7)*exp(x))/5040. (End)

Extensions

Terms a(35) onward added by G. C. Greubel, Jul 01 2019

A027970 a(n) = T(n, 2*n-8), T given by A027960.

Original entry on oeis.org

1, 4, 11, 29, 76, 196, 487, 1148, 2552, 5353, 10636, 20120, 36425, 63415, 106630, 173821, 275603, 426242, 644593, 955207, 1389626, 1987886, 2800249, 3889186, 5331634, 7221551, 9672794, 12822346, 16833919, 21901961, 28256096
Offset: 4

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Author

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Crossrefs

A column of triangle A026998.

Programs

  • GAP
    List([4..40], n-> (-1169280 +1119312*n -517700*n^2 +148092*n^3 -26551*n^4 +2688*n^5 -70*n^6 -12*n^7 +n^8)/40320); # G. C. Greubel, Jul 01 2019
  • Magma
    [(-1169280 +1119312*n -517700*n^2 +148092*n^3 -26551*n^4 +2688*n^5 -70*n^6 -12*n^7 +n^8)/40320: n in [4..40]]; // G. C. Greubel, Jul 01 2019
    
  • Mathematica
    Table[(-1169280 +1119312*n -517700*n^2 +148092*n^3 -26551*n^4 +2688*n^5 -70*n^6 -12*n^7 +n^8)/40320, {n, 4, 40}] (* G. C. Greubel, Jul 01 2019 *)
  • PARI
    Vec(x^4*(x^8-5*x^7+11*x^6-10*x^5-x^4+10*x^3-11*x^2+5*x-1)/(x-1)^9 + O(x^40)) \\ Colin Barker, Nov 25 2014
    
  • PARI
    for(n=4,40, print1((-1169280 +1119312*n -517700*n^2 +148092*n^3 -26551*n^4 +2688*n^5 -70*n^6 -12*n^7 +n^8)/40320, ", ")) \\ G. C. Greubel, Jul 01 2019
    
  • Sage
    [(-1169280 +1119312*n -517700*n^2 +148092*n^3 -26551*n^4 +2688*n^5 -70*n^6 -12*n^7 +n^8)/40320 for n in (4..40)] # G. C. Greubel, Jul 01 2019
    

Formula

Sequence satisfies an 8-degree polynomial approximating A002878.
a(n) = (-1169280 +1119312*n -517700*n^2 +148092*n^3 -26551*n^4 +2688*n^5 -70*n^6 -12*n^7 +n^8)/40320. - Colin Barker, Nov 25 2014
G.f.: x^4*(x^8-5*x^7+11*x^6-10*x^5-x^4+10*x^3-11*x^2+5*x-1) / (x-1)^9. - Colin Barker, Nov 25 2014
From G. C. Greubel, Jul 01 2019: (Start)
a(n) = A027971(n+1) - A027971(n).
E.g.f.: (1169280 + 443520*x + 80640*x^2 + 6720*x^3 +(-1169280 +725760*x -221760*x^2 +47040*x^3 -6720*x^4 +1008*x^5 -56*x^6 +16*x^7 +x^8)*exp(x) )/8!. (End)

A027971 T(n, 2n-9), T given by A027960.

Original entry on oeis.org

3, 7, 18, 47, 123, 319, 806, 1954, 4506, 9859, 20495, 40615, 77040, 140455, 247085, 420906, 696509, 1122751, 1767344, 2722551, 4112177, 6100063, 8900312, 12789498, 18121132, 25342683, 35015477, 47837823, 64671742
Offset: 5

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Author

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Crossrefs

A column of triangle A027011.

Programs

  • GAP
    a:=[3,7,18,47, 123,319,806,1954,4506,9859];; for n in [11..40] do 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]; od; a; # G. C. Greubel, Sep 26 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( x^5*(3 -2*x)*(1-7*x+23*x^2-44*x^3+55*x^4-44*x^5+23*x^6-7*x^7+x^8)/(1-x)^10 )); // G. C. Greubel, Sep 26 2019
    
  • Maple
    seq(coeff(series(x^5*(3-2*x)*(1 -7*x +23*x^2 -44*x^3 +55*x^4 -44*x^5 +23*x^6 -7*x^7 +x^8)/(1-x)^10, x, n+1), x, n), n = 5..40); # G. C. Greubel, Sep 26 2019
  • Mathematica
    LinearRecurrence[{10,-45,120,-210,252,-210,120,-45,10,-1}, {3,7,18,47, 123,319,806,1954,4506,9859},40] (* Harvey P. Dale, Aug 04 2017 *)
  • PARI
    Vec(-x^5*(2*x-3)*(x^8-7*x^7+23*x^6-44*x^5+55*x^4-44*x^3+23*x^2 -7*x+1)/(x-1)^10 + O(x^40)) \\ Colin Barker, Nov 25 2014
    
  • Sage
    def A027971_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x^5*(3-2*x)*(1-7*x+23*x^2-44*x^3+55*x^4-44*x^5+23*x^6-7*x^7 +x^8)/(1-x)^10 ).list()
    a=A027971_list(40); a[5:] # G. C. Greubel, Sep 26 2019
    

Formula

a(n) = (17055360 -16329024*n +7697736*n^2 -2299060*n^3 +462798*n^4 -60207*n^5 +4284*n^6 -30*n^7 -18*n^8 +n^9)/362880. - Colin Barker, Nov 25 2014
G.f.: x^5*(3-2*x)*(1 -7*x +23*x^2 -44*x^3 +55*x^4 -44*x^5 +23*x^6 -7*x^7 +x^8)/(1-x)^10. - Colin Barker, Nov 25 2014

A027972 T(n, 2n-10), T given by A027960.

Original entry on oeis.org

1, 4, 11, 29, 76, 199, 518, 1324, 3278, 7784, 17643, 38138, 78753, 155793, 296248, 543333, 964239, 1660748, 2783499, 4550843, 7273394, 11385571, 17485634, 26385946, 39175444, 57296576, 82639259, 117654736, 165492559
Offset: 5

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Author

Keywords

Crossrefs

A column of triangle A026998.

Programs

  • GAP
    a:=[1, 4, 11, 29, 76, 199, 518, 1324, 3278, 7784, 17643];; for n in [12..40] do a[n]:=11*a[n-1]-55*a[n-2]+165*a[n-3]-330*a[n-4]+462*a[n-5] -462*a[n-6]+330*a[n-7]-165*a[n-8]+55*a[n-9]-11*a[n-10]+a[n-11]; od; a; # G. C. Greubel, Sep 26 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( x^5*(1- 7*x+22*x^2-37*x^3+32*x^4+x^5-32*x^6+37*x^7-22*x^8+7*x^9 -x^10)/(1-x)^11 )); // G. C. Greubel, Sep 26 2019
    
  • Maple
    seq(coeff(series(x^5*(1 -7*x +22*x^2 -37*x^3 +32*x^4 +x^5 -32*x^6 +37*x^7 -22*x^8 +7*x^9 -x^10)/(1-x)^11, x, n+1), x, n), n = 5..40); # G. C. Greubel, Sep 26 2019
  • Mathematica
    Drop[CoefficientList[Series[x^5*(1 -7*x +22*x^2 -37*x^3 +32*x^4 +x^5 -32*x^6 +37*x^7 -22*x^8 +7*x^9 -x^10)/(1-x)^11, {x, 0, 40}], x], 5] (* G. C. Greubel, Sep 26 2019 *)
  • PARI
    my(x='x+O('x^40)); Vec(x^5*(1 -7*x +22*x^2 -37*x^3 +32*x^4 +x^5 -32*x^6 +37*x^7 -22*x^8 +7*x^9 -x^10)/(1-x)^11) \\ G. C. Greubel, Sep 26 2019
    
  • Sage
    def A027972_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x^5*(1 -7*x +22*x^2 -37*x^3 +32*x^4 +x^5 -32*x^6 +37*x^7 -22*x^8 +7*x^9 -x^10)/(1-x)^11 ).list()
    a=A027972_list(40); a[5:] # G. C. Greubel, Sep 26 2019
    

Formula

Sequence satisfies a 10-degree polynomial approximating A002878.
G.f.: x^5*(1 -7*x +22*x^2 -37*x^3 +32*x^4 +x^5 -32*x^6 +37*x^7 -22*x^8 +7*x^9 -x^10)/(1-x)^11. - R. J. Mathar, Jan 30 2011
a(n) = -76 +183941*n/2520 +386899*n^3/36288 -1747657*n^2/50400 -831241*n^4/362880 +11887*n^5/34560 -5807*n^6/172800 +41*n^7/24192 +n^8/60480 -n^9/145152 +n^10/3628800. - R. J. Mathar, Jan 30 2011

A027976 n-th diagonal sum of right justified array T given by A027960.

Original entry on oeis.org

1, 1, 4, 6, 10, 18, 29, 47, 78, 126, 204, 332, 537, 869, 1408, 2278, 3686, 5966, 9653, 15619, 25274, 40894, 66168, 107064, 173233, 280297, 453532, 733830, 1187362, 1921194, 3108557, 5029751, 8138310, 13168062, 21306372, 34474436, 55780809, 90255245, 146036056, 236291302, 382327358
Offset: 0

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Author

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Crossrefs

Programs

  • GAP
    a:=[1,1,4,6,10];; for n in [6..40] do a[n]:=a[n-1]+a[n-2]+a[n-3]-a[n-4]-a[n-5]; od; a; # G. C. Greubel, Sep 26 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1 + 2*x^2)/((1-x^3)*(1-x-x^2)) )); // G. C. Greubel, Sep 26 2019
    
  • Maple
    seq(coeff(series((1 + 2*x^2)/((1-x^3)*(1-x-x^2)), x, n+1), x, n), n = 0..40); # G. C. Greubel, Sep 26 2019
  • Mathematica
    LinearRecurrence[{1,1,1,-1,-1}, {1,1,4,6,10}, 41] (* or *) Table[ (Fibonacci[n+1] +LucasL[n+2] -2*Sin[2*Pi*n/3]/Sqrt[3] -2)/2, {n,0,40}] (* G. C. Greubel, Sep 26 2019 *)
  • PARI
    my(x='x+O('x^40)); Vec((1 + 2*x^2)/((1-x^3)*(1-x-x^2))) \\ G. C. Greubel, Sep 26 2019
    
  • Sage
    def A027976_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P((1 + 2*x^2)/((1-x^3)*(1-x-x^2))).list()
    A027976_list(40) # G. C. Greubel, Sep 26 2019
    

Formula

G.f.: (1 + 2*x^2)/((1-x^3)*(1-x-x^2)).
From G. C. Greubel, Sep 26 2019: (Start)
a(n) = (Fibonacci(n) + 4*Fibonacci(n+1) - A102283(n) - 2)/2.
a(n) = (Fibonacci(n+1) + Lucas(n+2) - 2*sin(2*Pi*n/3)/sqrt(3) - 2)/2. (End)

Extensions

Terms a(28) onward added by G. C. Greubel, Sep 26 2019

A027981 a(n) = Sum_{k=0..2*n} (k+1)*T(n,k), T given by A027960.

Original entry on oeis.org

1, 10, 40, 124, 340, 868, 2116, 4996, 11524, 26116, 58372, 129028, 282628, 614404, 1327108, 2850820, 6094852, 12976132, 27525124, 58195972, 122683396, 257949700, 541065220, 1132462084, 2365587460, 4932501508, 10267656196, 21340618756, 44291850244, 91804925956, 190052302852, 392989507588, 811748818948, 1675037245444, 3453153705988
Offset: 0

Views

Author

Keywords

Crossrefs

Cf. A027960.

Programs

Formula

a(2*n+1) = 6*(4*n+1) * 4^n + 4. - Ralf Stephan, Mar 22 2004
From R. J. Mathar, May 22 2013: (Start)
a(n) = 3*2^n*(2*n-1) + 4.
G.f.: (1 + 5*x - 2*x^2)/( (1-x)*(1-2*x)^2 ). (End)
a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3), with a(0)=1, a(1)=10, a(2)=40. - Harvey P. Dale, Apr 17 2015
E.g.f.: 3*(4*x - 1)*exp(2*x) + 4*exp(x). - Ilya Gutkovskiy, Apr 17 2016

Extensions

More terms added by G. C. Greubel, Jun 07 2025

A027975 a(n) is the n-th diagonal sum of left justified array T given by A027960.

Original entry on oeis.org

1, 1, 4, 5, 8, 12, 16, 23, 31, 42, 57, 76, 102, 136, 181, 241, 320, 425, 564, 748, 992, 1315, 1743, 2310, 3061, 4056, 5374, 7120, 9433, 12497, 16556, 21933, 29056, 38492, 50992, 67551, 89487, 118546, 157041, 208036, 275590, 365080, 483629, 640673, 848712, 1124305, 1489388, 1973020
Offset: 0

Views

Author

Keywords

Crossrefs

Cf. A027960.

Programs

  • GAP
    a:=[1,1,4,5];; for n in [5..40] do a[n]:=a[n-1]+a[n-2]-a[n-4]; od; a; # G. C. Greubel, Sep 26 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+2*x^2)/((1-x)*(1-x^2-x^3)) )); // G. C. Greubel, Sep 26 2019
    
  • Maple
    seq(coeff(series((1+2*x^2)/((1-x)*(1-x^2-x^3)), x, n+1), x, n), n = 0..40); # G. C. Greubel, Sep 26 2019
  • Mathematica
    CoefficientList[Series[(1+2*x^2)/((1-x)*(1-x^2-x^3)), {x,0,40}], x] (* or *) LinearRecurrence[{1,1,0,-1}, {1,1,4,5}, 41] (* G. C. Greubel, Sep 26 2019 *)
  • PARI
    my(x='x+O('x^40)); Vec((1+2*x^2)/((1-x)*(1-x^2-x^3))) \\ G. C. Greubel, Sep 26 2019
    
  • Sage
    def A027975_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1+2*x^2)/((1-x)*(1-x^2-x^3)) ).list()
    A027975_list(40) # G. C. Greubel, Sep 26 2019
    

Formula

G.f.: (1 + 2*x^2)/((1-x)*(1-x^2-x^3)).
a(n) = a(n-2) + a(n-3) + 3. - Greg Dresden, May 18 2020

Extensions

Terms a(32) onward added by G. C. Greubel, Sep 26 2019

A027977 a(n) = greatest number in row n of array T given by A027960.

Original entry on oeis.org

1, 3, 4, 8, 15, 28, 54, 101, 199, 373, 743, 1404, 2801, 5353, 10636, 20495, 40615, 78753, 155793, 303553, 599801, 1173183, 2316317, 4544731, 8968421, 17641499, 34801731, 68602923, 135308317, 267203186, 526966454, 1042217402, 2055373383, 4070330014, 8027429651, 15914813448, 31389204737, 62291326036, 122871494899
Offset: 0

Views

Author

Keywords

Crossrefs

Cf. A027960.

Programs

  • Mathematica
    T[n_, k_]:= T[n, k]= If[k<0 || k>2*n, 0, If[k==0 || k==2*n, 1, If[k==1, 3, T[n-1, k-2] + T[n-1, k-1]]]]; (* T = A027960 *)
    b[n_]:= b[n]= Table[T[n,k], {k,0,2*n}]//Union;
    A027977[n_]:= Max[b[n]];
    Table[A027977[n], {n,0,50}] (* G. C. Greubel, Jun 07 2025 *)
  • SageMath
    @CachedFunction
    def T(n, k): # T = A027960
        if (k<0 or k>2*n): return 0
        elif (k==0 or k==2*n): return 1
        elif (k==1): return 3
        else: return T(n-1, k-2) + T(n-1, k-1)
    def b(n): return sorted(set(flatten([T(n,k) for k in range(2*n+1)])))
    def A027977(n): return max(b(n))
    print([A027977(n) for n in range(51)]) # G. C. Greubel, Jun 07 2025

Extensions

More terms added by G. C. Greubel, Jun 07 2025

A027978 a(n) = self-convolution of row n of array T given by A027960.

Original entry on oeis.org

1, 11, 42, 145, 473, 1484, 4529, 13543, 39870, 115937, 333781, 953056, 2702497, 7618115, 21365778, 59657329, 165926609, 459905588, 1270819025, 3501855007, 9625627686, 26398369601, 72248624077, 197361589960, 538199264833
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • GAP
    List([0..40], n-> 2*(n+1)*Lucas(1,-1,2*n)[2] + Fibonacci(2*n-4) ); # G. C. Greubel, Oct 01 2019
  • Magma
    [2*(n+1)*Lucas(2*n) + Fibonacci(2*n-4): n in [0..40]]; // G. C. Greubel, Oct 01 2019
    
  • Maple
    with(combinat); f:=fibonacci; seq(2*(n+1)*(f(2*n+1) + f(2*n-1)) + f(2*n-4), n=0..40); # G. C. Greubel, Oct 01 2019
  • Mathematica
    Table[2*(n+1)*LucasL[2*n] + Fibonacci[2*n-4], {n, 0, 40}] (* G. C. Greubel, Oct 01 2019 *)
  • PARI
    vector(41, n, f=fibonacci; 2*n*(f(2*n-1) + f(2*n-3)) + f(2*n-6)) \\ G. C. Greubel, Oct 01 2019
    
  • Sage
    [2*(n+1)*lucas_number2(2*n,1,-1) + fibonacci(2*n-4) for n in (0..40)] # G. C. Greubel, Oct 01 2019
    

Formula

From Colin Barker, Feb 25 2015: (Start)
a(n) = 5*a(n-1) - 5*a(n-2) - 5*a(n-3) + 5*a(n-4) - a(n-5).
G.f.: (1 +5*x -13*x^2 +8*x^3)/(1-3*x+x^2)^2. (End)
a(n) = 2*(n+1)*Lucas(2*n) + Fibonacci(2*n-4). - G. C. Greubel, Oct 01 2019

A027979 a(n) = Sum_{k=0..n} T(n,k)*T(n,2n-k), T given by A027960.

Original entry on oeis.org

1, 10, 29, 97, 297, 904, 2685, 7876, 22823, 65533, 186691, 528370, 1486969, 4164382, 11613137, 32264089, 89339325, 246645436, 679111413, 1865340568, 5112351131, 13983383605, 38177371159, 104055773542, 283171508977
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • GAP
    List([0..40], n-> (n+1)*Lucas(1,-1,2*n)[2] + 3*Fibonacci(2*n) -(-1)^n ); # G. C. Greubel, Oct 01 2019
  • Magma
    [(n+1)*Lucas(2*n) + 3*Fibonacci(2*n) -(-1)^n: n in [0..40]]; // G. C. Greubel, Oct 01 2019
    
  • Maple
    f:= combinat[fibonacci]: seq((n+1)*(f(2*n+1) + f(2*n-1)) + 3*f(2*n) -(-1)^n, n=0..40); # G. C. Greubel, Oct 01 2019
  • Mathematica
    Table[(n+1)*LucasL[2*n] +3*Fibonacci[2*n] -(-1)^n, {n,0,40}] (* G. C. Greubel, Oct 01 2019 *)
  • PARI
    vector(41, n, f=fibonacci; n*(f(2*n-1) + f(2*n-3)) + 3*f(2*n-2) +(-1)^n) \\ G. C. Greubel, Oct 01 2019
    
  • Sage
    [(n+1)*lucas_number2(2*n,1,-1) + 3*fibonacci(2*n) -(-1)^n for n in (0..40)] # G. C. Greubel, Oct 01 2019
    

Formula

G.f.: (1 +5*x -16*x^2 +7*x^3 +2*x^4)/((1+x)*(1-3*x+x^2)^2). - Colin Barker, Nov 25 2014
a(n) = (n+1)*Lucas(2*n) + 3*Fibonacci(2*n) - (-1)^n. - G. C. Greubel, Oct 01 2019
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