A035598
Number of points of L1 norm 4 in cubic lattice Z^n.
Original entry on oeis.org
0, 2, 16, 66, 192, 450, 912, 1666, 2816, 4482, 6800, 9922, 14016, 19266, 25872, 34050, 44032, 56066, 70416, 87362, 107200, 130242, 156816, 187266, 221952, 261250, 305552, 355266, 410816, 472642, 541200, 616962, 700416, 792066
Offset: 0
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
- Milan Janjic and Boris Petkovic, A Counting Function, arXiv preprint arXiv:1301.4550 [math.CO], 2013. - _N. J. A. Sloane_, Feb 13 2013
- Milan Janjic and Boris Petkovic, A Counting Function Generalizing Binomial Coefficients and Some Other Classes of Integers, J. Int. Seq. 17 (2014), Article 14.3.5.
- Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
- Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
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[( 2*n^4 +4*n^2 )/3: n in [0..40]]; // Vincenzo Librandi, Apr 22 2012
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f := proc(d,m) local i; sum( 2^i*binomial(d,i)*binomial(m-1,i-1),i=1..min(d,m)); end; # n=dimension, m=norm
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CoefficientList[Series[2*x*(1+x)^3/(1-x)^5,{x,0,40}],x] (* Vincenzo Librandi, Apr 22 2012 *)
LinearRecurrence[{5,-10,10,-5,1},{0,2,16,66,192},50] (* Harvey P. Dale, Dec 11 2019 *)
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a(n)=2*n^2*(n^2+2)/3 \\ Charles R Greathouse IV, Dec 07 2011
A035599
Number of points of L1 norm 5 in cubic lattice Z^n.
Original entry on oeis.org
0, 2, 20, 102, 360, 1002, 2364, 4942, 9424, 16722, 28004, 44726, 68664, 101946, 147084, 207006, 285088, 385186, 511668, 669446, 864008, 1101450, 1388508, 1732590, 2141808, 2625010, 3191812, 3852630, 4618712, 5502170, 6516012
Offset: 0
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
- M. Janjic and B. Petkovic, A Counting Function, arXiv preprint arXiv:1301.4550 [math.CO], 2013. - _N. J. A. Sloane_, Feb 13 2013
- M. Janjic, B. Petkovic, A Counting Function Generalizing Binomial Coefficients and Some Other Classes of Integers, J. Int. Seq. 17 (2014) # 14.3.5.
- Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
- Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
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[(4*n^4+20*n^2+6)*n/15: n in [0..30]]; // Vincenzo Librandi, Apr 23 2012
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f := proc(d,m) local i; sum( 2^i*binomial(d,i)*binomial(m-1,i-1),i=1..min(d,m)); end; # n=dimension, m=norm
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CoefficientList[Series[2*x*(1+x)^4/(1-x)^6,{x,0,33}],x] (* Vincenzo Librandi, Apr 23 2012 *)
LinearRecurrence[{6,-15,20,-15,6,-1},{0,2,20,102,360,1002},40] (* Harvey P. Dale, Dec 30 2023 *)
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a(n)=(4*n^5+20*n^3+6*n)/15 \\ Charles R Greathouse IV, Dec 07 2011
A137891
Number of (directed) Hamiltonian paths in the graph join C_n + C_n of two cycles.
Original entry on oeis.org
720, 13824, 383000, 14804640, 764340024, 50913153536, 4256161751448, 436618291524000, 53955264479804600, 7908071556041000064, 1356709951589099693976, 269380212536429979520928, 61297096735652845698099000, 15847986814197933588682229760, 4620315237160994963528810238104
Offset: 3
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b[n_, k_] := If[k == 0, 0, Sum[j*Min[2, j] * Sum[ Binomial[n - j - k, kk - 1]*Binomial[k - 1, kk]*2^kk, {kk, 0, Min[k - 1, n - j - k + 1]}], {j, 1, n - k + 1}]];
Flatten[{{2, 24}, Table[Sum[2*k!*b[n, k]*(k!*b[n, k] + (k - 1)!*b[n, k - 1]), {k, 1, n}], {n, 3, 20}]}] (* Vaclav Kotesovec, Mar 08 2016, after Andrew Howroyd *)
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B(n)=polcoef(1/(1 - x*y*(2/(1 - x) - 1)) + O(x*x^n), n)
a(n)={my(v=Vecrev(B(n))); 2*n^2*sum(k=1, n, my(t=v[1+k]*(k-1)!); t*(t + if(k>1, v[k]*(k-2)!)))} \\ Andrew Howroyd, Jan 10 2025
A336521
Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) is the coefficient of x^(k*n) in expansion of ( (1 + x)/(1 - x) )^n.
Original entry on oeis.org
1, 1, 1, 1, 2, 1, 1, 2, 8, 1, 1, 2, 16, 38, 1, 1, 2, 24, 146, 192, 1, 1, 2, 32, 326, 1408, 1002, 1, 1, 2, 40, 578, 4672, 14002, 5336, 1, 1, 2, 48, 902, 11008, 69002, 142000, 28814, 1, 1, 2, 56, 1298, 21440, 216002, 1038984, 1459810, 157184, 1, 1, 2, 64, 1766, 36992, 525002, 4320608, 15856206, 15158272, 864146, 1
Offset: 0
Square array begins:
1, 1, 1, 1, 1, 1, ...
1, 2, 2, 2, 2, 2, ...
1, 8, 16, 24, 32, 40, ...
1, 38, 146, 326, 578, 902, ...
1, 192, 1408, 4672, 11008, 21440, ...
1, 1002, 14002, 69002, 216002, 525002, ...
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T[n_, 0] := 1; T[n_, k_] := Sum[Binomial[n, j] * Binomial[k*n + j - 1, n - 1], {j, 0, n}]; Table[T[k, n - k], {n, 0, 10}, {k, 0, n}] // Flatten (* Amiram Eldar, Jul 24 2020 *)
A378318
Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,0) = 0^n and T(n,k) = k * Sum_{r=0..n} binomial(n,r) * binomial(3*r+k,n)/(3*r+k) for k > 0.
Original entry on oeis.org
1, 1, 0, 1, 2, 0, 1, 4, 6, 0, 1, 6, 16, 30, 0, 1, 8, 30, 84, 170, 0, 1, 10, 48, 170, 496, 1050, 0, 1, 12, 70, 296, 1050, 3140, 6846, 0, 1, 14, 96, 470, 1920, 6846, 20832, 46374, 0, 1, 16, 126, 700, 3210, 12936, 46374, 142932, 323154, 0, 1, 18, 160, 994, 5040, 22402, 89712, 323154, 1005856, 2301618, 0
Offset: 0
Square array begins:
1, 1, 1, 1, 1, 1, 1, ...
0, 2, 4, 6, 8, 10, 12, ...
0, 6, 16, 30, 48, 70, 96, ...
0, 30, 84, 170, 296, 470, 700, ...
0, 170, 496, 1050, 1920, 3210, 5040, ...
0, 1050, 3140, 6846, 12936, 22402, 36492, ...
0, 6846, 20832, 46374, 89712, 159390, 266800, ...
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T(n, k, t=0, u=3) = if(k==0, 0^n, k*sum(r=0, n, binomial(n, r)*binomial(t*n+u*r+k, n)/(t*n+u*r+k)));
matrix(7, 7, n, k, T(n-1, k-1))
A035706
Coordination sequence for 11-dimensional cubic lattice.
Original entry on oeis.org
1, 22, 242, 1782, 9922, 44726, 170610, 568150, 1690370, 4573910, 11414898, 26572086, 58227906, 121023606, 240089586, 457018518, 838478850, 1488341910, 2564399090, 4300978550, 7039035586, 11265589302, 17664712562, 27182654422
Offset: 0
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
- Seiichi Manyama, Table of n, a(n) for n = 0..10000
- J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
- Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
- Index entries for linear recurrences with constant coefficients, signature (11, -55, 165, -330, 462, -462, 330, -165, 55, -11, 1).
A035734
Coordination sequence for 39-dimensional cubic lattice.
Original entry on oeis.org
1, 78, 3042, 79118, 1544322, 24138894, 314835170, 3525405390, 34608828930, 302685166030, 2388631358178, 17185219312014, 113694451659906, 696708049377294, 3979111519381986, 21295193543579982, 107295791104411650
Offset: 0
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
- Seiichi Manyama, Table of n, a(n) for n = 0..10000
- J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
- Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
- Index entries for linear recurrences with constant coefficients, signature (39, -741, 9139, -82251, 575757, -3262623, 15380937, -61523748, 211915132, -635745396, 1676056044, -3910797436, 8122425444, -15084504396, 25140840660, -37711260990, 51021117810, -62359143990, 68923264410, -68923264410, 62359143990, -51021117810, 37711260990, -25140840660, 15084504396, -8122425444, 3910797436, -1676056044, 635745396, -211915132, 61523748, -15380937, 3262623, -575757, 82251, -9139, 741, -39, 1).
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CoefficientList[Series[((1+n)/(1-n))^39,{n,0,20}],n] (* Harvey P. Dale, Apr 09 2015 *)
A378317
Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,0) = 0^n and T(n,k) = k * Sum_{r=0..n} binomial(n,r) * binomial(2*r+k,n)/(2*r+k) for k > 0.
Original entry on oeis.org
1, 1, 0, 1, 2, 0, 1, 4, 4, 0, 1, 6, 12, 12, 0, 1, 8, 24, 40, 40, 0, 1, 10, 40, 92, 144, 144, 0, 1, 12, 60, 176, 360, 544, 544, 0, 1, 14, 84, 300, 752, 1440, 2128, 2128, 0, 1, 16, 112, 472, 1400, 3200, 5872, 8544, 8544, 0, 1, 18, 144, 700, 2400, 6352, 13664, 24336, 35008, 35008, 0
Offset: 0
Square array begins:
1, 1, 1, 1, 1, 1, 1, ...
0, 2, 4, 6, 8, 10, 12, ...
0, 4, 12, 24, 40, 60, 84, ...
0, 12, 40, 92, 176, 300, 472, ...
0, 40, 144, 360, 752, 1400, 2400, ...
0, 144, 544, 1440, 3200, 6352, 11616, ...
0, 544, 2128, 5872, 13664, 28480, 54768, ...
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T(n, k, t=0, u=2) = if(k==0, 0^n, k*sum(r=0, n, binomial(n, r)*binomial(t*n+u*r+k, n)/(t*n+u*r+k)));
matrix(7, 7, n, k, T(n-1, k-1))
A035708
Coordination sequence for 13-dimensional cubic lattice.
Original entry on oeis.org
1, 26, 338, 2938, 19266, 101946, 454610, 1761370, 6065410, 18892250, 53972178, 143027898, 354870594, 830764794, 1847023698, 3921503898, 7988589570, 15677993370, 29746958930, 54734043130, 97926519106, 170763634106, 290835675858
Offset: 0
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
- Seiichi Manyama, Table of n, a(n) for n = 0..10000
- J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
- Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
- Index entries for linear recurrences with constant coefficients, signature (13, -78, 286, -715, 1287, -1716, 1716, -1287, 715, -286, 78, -13, 1).
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CoefficientList[Series[((1+x)/(1-x))^13,{x,0,30}],x] (* or *) LinearRecurrence[ {13,-78,286,-715,1287,-1716,1716,-1287,715,-286,78,-13,1},{1,26,338,2938,19266,101946,454610,1761370,6065410,18892250,53972178,143027898,354870594,830764794},30] (* Harvey P. Dale, Nov 07 2017 *)
A125190
Number of ascents in all Schroeder paths of length 2n.
Original entry on oeis.org
0, 1, 6, 32, 170, 912, 4942, 27008, 148626, 822560, 4573910, 25534368, 143027898, 803467056, 4524812190, 25537728000, 144411206178, 818017823808, 4640757865126, 26364054632480, 149959897539018, 853941394691792, 4867745532495086, 27773897706129792
Offset: 0
a(2) = 6 because the Schroeder paths of length 4 are HH, H(U)D, (U)DH, (U)D(U)D, (U)HD and (UU)DD, having a total of 6 ascents (shown between parentheses).
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R:=(1-z-sqrt(1-6*z+z^2))/2/z: G:=z*R*(1+z*R)/sqrt(1-6*z+z^2): Gser:=series(G,z=0,30): seq(coeff(Gser,z,n),n=0..25);
# second Maple program:
a:= proc(n) option remember;
`if`(n<3, [0,1,6][n+1], ((204*n^2-411*n+198)*a(n-1)
+(-34*n^2+68*n+96)*a(n-2) +(3*n-12)*a(n-3))/(2*n*(17*n-26)))
end:
seq(a(n), n=0..30); # Alois P. Heinz, Oct 20 2012
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CoefficientList[Series[x*(1-x-Sqrt[1-6*x+x^2])/(2*x)*(1+x*(1-x-Sqrt[1-6*x+x^2])/(2*x))/Sqrt[1-6*x+x^2], {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 19 2012 *)
a[n_] := Sum[ Binomial[n+1, n-i-1]*Binomial[n+i, n], {i, 0, n-1}]; (* or *) a[n_] := Hypergeometric2F1[1-n, 1+n, 3, -1]*n*(n+1)/2; Table[a[n], {n, 0, 23}] (* Jean-François Alcover, Feb 05 2013, after Vladimir Kruchinin *)
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A125190 = lambda n : (n^2+n)*hypergeometric([1-n, n+1], [3], -1)/2
[round(A125190(n).n(100)) for n in (0..23)] # Peter Luschny, Sep 17 2014
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