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 1-5 of 5 results.

A000582 a(n) = binomial coefficient C(n,9).

Original entry on oeis.org

1, 10, 55, 220, 715, 2002, 5005, 11440, 24310, 48620, 92378, 167960, 293930, 497420, 817190, 1307504, 2042975, 3124550, 4686825, 6906900, 10015005, 14307150, 20160075, 28048800, 38567100, 52451256, 70607460, 94143280, 124403620, 163011640, 211915132
Offset: 9

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Author

Keywords

Comments

Figurate numbers based on 9-dimensional regular simplex. - Jonathan Vos Post, Nov 28 2004
Product of 9 consecutive numbers divided by 9!. - Artur Jasinski, Dec 02 2007
In this sequence there are no primes. - Artur Jasinski, Dec 02 2007
a(9+n) gives the number of words with n letters over the alphabet {0,1,..,9} such that these letters are read from left to right in weakly increasing (nondecreasing) order. - R. J. Cano, Jul 20 2014
a(n) = fallfac(n, 9)/9! = binomial(n, 9) is also the number of independent components of an antisymmetric tensor of rank 9 and dimension n >= 9 (for n=1..8 this becomes 0). Here fallfac is the falling factorial. - Wolfdieter Lang, Dec 10 2015
From Juergen Will, Jan 23 2016: (Start)
Number of compositions (ordered partitions) of n+1 into exactly 10 parts.
Number of weak compositions (ordered weak partitions) of n-9 into exactly 10 parts. (End)
Number of integers divisible by 9 in the interval [0, 10^(n-8)-1]. - Miquel Cerda, Jul 02 2017

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 828.
  • Albert H. Beiler, Recreations in the Theory of Numbers, Dover, NY, 1964, p. 196.
  • L. E. Dickson, History of the Theory of Numbers. Carnegie Institute Public. 256, Washington, DC, Vol. 1, 1919; Vol. 2, 1920; Vol. 3, 1923, see vol. 2, p. 7.
  • J. C. P. Miller, editor, Table of Binomial Coefficients. Royal Society Mathematical Tables, Vol. 3, Cambridge Univ. Press, 1954.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

Formula

G.f.: x^9/(1-x)^10.
a(n) = -A110555(n+1, 9). - Reinhard Zumkeller, Jul 27 2005
a(n+8) = n(n+1)(n+2)(n+3)(n+4)(n+5)(n+6)(n+7)(n+8)/9!. - Artur Jasinski, Dec 02 2007; R. J. Mathar, Jul 07 2009
Sum_{k>=9} 1/a(k) = 9/8. - Tom Edgar, Sep 10 2015
Sum_{n>=9} (-1)^(n+1)/a(n) = A001787(9)*log(2) - A242091(9)/8! = 2304*log(2) - 446907/280 = 0.9146754386... - Amiram Eldar, Dec 10 2020

Extensions

Formulas referring to other offsets rewritten by R. J. Mathar, Jul 07 2009

A053123 Triangle of coefficients of shifted Chebyshev's S(n,x-2) = U(n,x/2-1) polynomials (exponents of x in decreasing order).

Original entry on oeis.org

1, 1, -2, 1, -4, 3, 1, -6, 10, -4, 1, -8, 21, -20, 5, 1, -10, 36, -56, 35, -6, 1, -12, 55, -120, 126, -56, 7, 1, -14, 78, -220, 330, -252, 84, -8, 1, -16, 105, -364, 715, -792, 462, -120, 9, 1, -18, 136, -560, 1365, -2002, 1716, -792, 165, -10, 1, -20, 171, -816, 2380, -4368, 5005, -3432, 1287, -220, 11, 1
Offset: 0

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Author

Keywords

Comments

T(n,m) = A053122(n,n-m).
G.f. for row polynomials and row sums same as in A053122.
Unsigned column sequences are A000012, A005843, A014105, A002492 for m=0..3, resp. and A053126-A053131 for m=4..9.
This is also the coefficient triangle for Chebyshev's U(2*n+1,x) polynomials expanded in decreasing odd powers of (2*x): U(2*n+1,x) = Sum_{m=0..n} T(n,m)*(2*x)^(2*(n-m)+1). See the W. Lang link given in A053125.
Unsigned version is mirror image of A078812. - Philippe Deléham, Dec 02 2008

Examples

			Triangle begins:
  1;
  1,  -2;
  1,  -4,  3;
  1,  -6, 10,   -4;
  1,  -8, 21,  -20,   5;
  1, -10, 36,  -56,  35,  -6;
  1, -12, 55, -120, 126, -56, 7; ...
E.g. fourth row (n=3) {1,-6,10,-4} corresponds to polynomial S(3,x-2) = x^3-6*x^2+10*x-4.
		

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 795
  • Theodore J. Rivlin, Chebyshev polynomials: from approximation theory to algebra and number theory, 2. ed., Wiley, New York, 1990.
  • Stephen Barnett, "Matrices: Methods and Applications", Oxford University Press, 1990, p. 132, 343.

Crossrefs

Programs

  • GAP
    Flat(List([0..10], n-> List([0..n], k-> (-1)^k*Binomial(2*n-k+1,k) ))); # G. C. Greubel, Jul 23 2019
  • Magma
    [(-1)^k*Binomial(2*n-k+1,k): k in [0..n], n in [0..10]]; // G. C. Greubel, Jul 23 2019
    
  • Maple
    A053123 := proc(n,m)
        (-1)^m*binomial(2*n+1-m,m) ;
    end proc: # R. J. Mathar, Sep 08 2013
  • Mathematica
    T[n_, m_]:= (-1)^m*Binomial[2*n+1-m, m]; Table[T[n, m], {n, 0, 11}, {m, 0, n}]//Flatten (* Jean-François Alcover, Mar 05 2014, after R. J. Mathar *)
  • PARI
    for(n=0,10, for(k=0,n, print1((-1)^k*binomial(2*n-k+1,k), ", "))) \\ G. C. Greubel, Jul 23 2019
    
  • Sage
    [[(-1)^k*binomial(2*n-k+1,k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Jul 23 2019
    

Formula

T(n, m) = 0 if n
T(n, m) = -2*T(n-1, m-1) + T(n-1, m) - T(n-2, m-2), T(n, -2) = 0, T(-2, m) = 0, T(n, -1) = 0 = T(-1, m), T(0, 0) = 1, T(n, m) = 0 if n
G.f. for m-th column (signed triangle): ((-1)^m)*x^m*Po(m+1, x)/(1-x)^(m+1), with Po(k, x) := Sum_{j=0..floor(k/2)} binomial(k, 2*j+1)*x^j.
The n-th degree polynomial is the characteristic equation for an n X n tridiagonal matrix with (diagonal = all 2's, sub and superdiagonals all -1's and the rest 0's), exemplified by the 4X4 matrix M = [2 -1 0 0 / -1 2 -1 0 / 0 -1 2 -1 / 0 0 -1 2]. - Gary W. Adamson, Jan 05 2005
Sum_{m=0..n} T(n,m)*(c(n))^(2*n-2*m) = 1/c(n), where c(n) = 2*cos(Pi/(2*n+3)). - L. Edson Jeffery, Sep 13 2013

A053138 Binomial coefficients C(2*n+9,9).

Original entry on oeis.org

1, 55, 715, 5005, 24310, 92378, 293930, 817190, 2042975, 4686825, 10015005, 20160075, 38567100, 70607460, 124403620, 211915132, 350343565, 563921995, 886163135, 1362649145, 2054455634, 3042312350, 4431613550, 6358402050, 8996462475, 12565671261, 17341763505
Offset: 0

Keywords

Comments

Even-indexed members of tenth column of Pascal's triangle A007318.
Number of standard tableaux of shape (2n+1,1^9). - Emeric Deutsch, May 30 2004

Crossrefs

Programs

Formula

a(n) = binomial(2*n+9, 9) = A000582(2*n+9).
G.f.: (1 + 45*x + 210*x^2 + 210*x^3 + 45*x^4 + x^5) / (1-x)^10.
G.f.: (1 + x) * (x^4 + 44*x^3 + 166*x^2 + 44*x + 1) / (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) for n > 9. - Wesley Ivan Hurt, Dec 05 2016
From Amiram Eldar, Nov 03 2022: (Start)
Sum_{n>=0} 1/a(n) = 1152*log(2) - 27912/35.
Sum_{n>=0} (-1)^n/a(n) = 36*Pi - 3924/35. (End)

A053133 One half of binomial coefficients binomial(2*n-8,9).

Original entry on oeis.org

5, 110, 1001, 5720, 24310, 83980, 248710, 653752, 1562275, 3453450, 7153575, 14024400, 26225628, 47071640, 81505820, 136719440, 222945905, 354465254, 550858165, 838553320, 1252716850, 1839537700, 2658968130, 3787984200, 5324436975, 7391571330, 10143295635
Offset: 9

Keywords

Crossrefs

Cf. A053131.

Programs

Formula

a(n) = binomial(2*n-8, 9)/2.
G.f.: (5+60*x+126*x^2+60*x^3+5*x^4)/(1-x)^10.
a(n) = A053131(n)/2.
From Amiram Eldar, Nov 03 2022: (Start)
Sum_{n>=9} 1/a(n) = 223611/140 - 2304*log(2).
Sum_{n>=9} (-1)^(n+1)/a(n) = 144*log(2) - 13947/140. (End)

A196790 Binomial coefficients C(2*n-9,10).

Original entry on oeis.org

11, 286, 3003, 19448, 92378, 352716, 1144066, 3268760, 8436285, 20030010, 44352165, 92561040, 183579396, 348330136, 635745396, 1121099408, 1917334783, 3190187286, 5178066751, 8217822536, 12777711870, 19499099620, 29248649430, 43183019880, 62828356305, 90177170226
Offset: 10

Author

Vincenzo Librandi, Oct 07 2011

Keywords

Programs

  • Magma
    [Binomial(2*n-9,10): n in [10..40]];
  • Mathematica
    a[n_] := Binomial[2*n - 9, 10]; Array[a, 20, 10] (* Amiram Eldar, Oct 21 2022 *)

Formula

G.f.: x^10*(11+165*x+462*x^2+330*x^3+55*x^4+x^5) / (1-x)^11. - R. J. Mathar, Oct 08 2011
From Amiram Eldar, Oct 21 2022: (Start)
Sum_{n>=10} 1/a(n) = 447187/252 - 2560*log(2).
Sum_{n>=10} (-1)^n/a(n) = 40*Pi + 80*log(2) - 6517/36. (End)
Showing 1-5 of 5 results.