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 1-7 of 7 results.

A112468 Riordan array (1/(1-x), x/(1+x)).

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 1, -1, 1, 1, 0, 2, -2, 1, 1, 1, -2, 4, -3, 1, 1, 0, 3, -6, 7, -4, 1, 1, 1, -3, 9, -13, 11, -5, 1, 1, 0, 4, -12, 22, -24, 16, -6, 1, 1, 1, -4, 16, -34, 46, -40, 22, -7, 1, 1, 0, 5, -20, 50, -80, 86, -62, 29, -8, 1, 1, 1, -5, 25, -70, 130, -166, 148, -91, 37, -9, 1, 1, 0, 6, -30, 95, -200, 296, -314, 239, -128, 46, -10, 1
Offset: 0

Views

Author

Paul Barry, Sep 06 2005

Keywords

Comments

Row sums are A040000. Diagonal sums are A112469. Inverse is A112467. Row sums of k-th power are 1, k+1, k+1, k+1, .... Note that C(n,k) = Sum_{j=0..n-k} C(n-j-1, n-k-j).
Equals row reversal of triangle A112555 up to sign, where log(A112555) = A112555 - I. Unsigned row sums equals A052953 (Jacobsthal numbers + 1). Central terms of even-indexed rows are a signed version of A072547. Sums of squared terms in rows yields A112556, which equals the first differences of the unsigned central terms. - Paul D. Hanna, Jan 20 2006
Sum_{k=0..n} T(n,k)*x^k = A000012(n), A040000(n), A005408(n), A033484(n), A048473(n), A020989(n), A057651(n), A061801(n), A238275(n), A238276(n), A138894(n), A090843(n), A199023(n) for x = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 respectively (see the square array in A112739). - Philippe Deléham, Feb 22 2014

Examples

			Triangle starts
  1;
  1,  1;
  1,  0,  1;
  1,  1, -1,  1;
  1,  0,  2, -2,  1;
  1,  1, -2,  4, -3,  1;
  1,  0,  3, -6,  7, -4,  1;
Matrix log begins:
  0;
  1,  0;
  1,  0,  0;
  1,  1, -1,  0;
  1,  1,  1, -2,  0;
  1,  1,  1,  1, -3,  0; ...
Production matrix begins
  1,  1,
  0, -1,  1,
  0,  0, -1,  1,
  0,  0,  0, -1,  1,
  0,  0,  0,  0, -1,  1,
  0,  0,  0,  0,  0, -1,  1,
  0,  0,  0,  0,  0,  0, -1,  1.
- _Paul Barry_, Apr 08 2011
		

Crossrefs

Cf. A174294, A174295, A174296, A174297. - Mats Granvik, Mar 15 2010
Cf. A072547 (central terms), A112555 (reversed rows), A112465, A052953, A112556, A112739, A119258.
See A279006 for another version.

Programs

  • GAP
    T:= function(n,k)
        if k=0 or k=n then return 1;
        else return T(n-1,k-1) - T(n-1,k);
        fi;
      end;
    Flat(List([0..12], n-> List([0..n], k-> T(n,k) ))); # G. C. Greubel, Nov 13 2019
  • Haskell
    a112468 n k = a112468_tabl !! n !! k
    a112468_row n = a112468_tabl !! n
    a112468_tabl = iterate (\xs -> zipWith (-) ([2] ++ xs) (xs ++ [0])) [1]
    -- Reinhard Zumkeller, Jan 03 2014
    
  • Magma
    function T(n,k)
      if k eq 0 or k eq n then return 1;
      else return T(n-1,k-1) - T(n-1,k);
      end if;
      return T;
    end function;
    [T(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Nov 13 2019
    
  • Maple
    T := (n,k,m) -> (1-m)^(-n+k)-m^(k+1)*pochhammer(n-k,k+1)*hypergeom( [1,n+1],[k+2],m)/(k+1)!; A112468 := (n,k) -> T(n,n-k,-1);
    seq(print(seq(simplify(A112468(n,k)),k=0..n)),n=0..10); # Peter Luschny, Jul 25 2014
  • Mathematica
    T[n_, 0] = 1; T[n_, n_] = 1; T[n_, k_ ]:= T[n, k] = T[n-1, k-1] - T[n-1, k]; Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten (* Jean-François Alcover, Mar 06 2013 *)
  • PARI
    {T(n,k)=local(m=1,x=X+X*O(X^n),y=Y+Y*O(Y^k)); polcoeff(polcoeff((1+(m-1)*x)*(1+m*x)/(1+m*x-x*y)/(1-x),n,X),k,Y)} \\ Paul D. Hanna, Jan 20 2006
    
  • PARI
    T(n,k) = if(k==0 || k==n, 1, T(n-1, k-1) - T(n-1, k)); \\ G. C. Greubel, Nov 13 2019
    
  • Sage
    @CachedFunction
    def T(n, k):
        if (k<0 or n<0): return 0
        elif (k==0 or k==n): return 1
        else: return T(n-1, k-1) - T(n-1, k)
    [[T(n, k) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Nov 13 2019
    

Formula

Triangle T(n,k) read by rows: T(n,0)=1, T(n,k) = T(n-1,k-1) - T(n-1,k). - Mats Granvik, Mar 15 2010
Number triangle T(n, k)= Sum_{j=0..n-k} C(n-j-1, n-k-j)*(-1)^(n-k-j).
G.f. of matrix power T^m: (1+(m-1)*x)*(1+m*x)/(1+m*x-x*y)/(1-x). G.f. of matrix log: x*(1-2*x*y+x^2*y)/(1-x*y)^2/(1-x). - Paul D. Hanna, Jan 20 2006
T(n, k) = R(n,n-k,-1) where R(n,k,m) = (1-m)^(-n+k)-m^(k+1)*Pochhammer(n-k,k+1)*hyper2F1([1,n+1],[k+2],m)/(k+1)!. - Peter Luschny, Jul 25 2014

A072547 Main diagonal of the array in which first column and row are filled alternatively with 1's or 0's and then T(i,j) = T(i-1,j) + T(i,j-1).

Original entry on oeis.org

1, 0, 2, 6, 22, 80, 296, 1106, 4166, 15792, 60172, 230252, 884236, 3406104, 13154948, 50922986, 197519942, 767502944, 2987013068, 11641557716, 45429853652, 177490745984, 694175171648, 2717578296116, 10648297329692, 41757352712480
Offset: 1

Views

Author

Benoit Cloitre, Aug 05 2002

Keywords

Comments

A Catalan transform of A078008 under the mapping g(x)->g(xc(x)). - Paul Barry, Nov 13 2004
Number of positive terms in expansion of (x_1 + x_2 + ... + x_{n-1} - x_n)^n. - Sergio Falcon, Feb 08 2007
Hankel transform is A088138(n+1). - Paul Barry, Feb 17 2009
Without the beginning "1", we obtain the first diagonal over the principal diagonal of the array notified by B. Cloitre in A026641 and used by R. Choulet in A172025, and from A172061 to A172066. - Richard Choulet, Jan 25 2010
Also central terms of triangles A108561 and A112465. - Reinhard Zumkeller, Jan 03 2014
With offset 0 and for p prime, the p-th term is divisible by p. - F. Chapoton, Dec 03 2021

Examples

			The array begins:
  1 0 1 0 1..
  0 0 1 1 2..
  1 1 2 3 5..
  0 1 3 6 11..
so sequence begins : 1, 0, 2, 6, ...
		

References

  • L. W. Shapiro and C. J. Wang, Generating identities via 2 X 2 matrices, Congressus Numerantium, 205 (2010), 33-46.

Crossrefs

Programs

  • Haskell
    a072547 n = a108561 (2 * (n - 1)) (n - 1)
    -- Reinhard Zumkeller, Jan 03 2014
    
  • Magma
    R:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( x*(1 + Sqrt(1-4*x))/(Sqrt(1-4*x)*(3-Sqrt(1-4*x))) )); // G. C. Greubel, Feb 17 2019
    
  • Maple
    taylor( (2/(3*sqrt(1-4*z)-1+4*z))*((1-sqrt(1-4*z))/(2*z))^(-1),z=0,42); for n from -1 to 40 do a(n):=sum('(-1)^(p)*binomial(2n-p+1,1+n-p)',p=0..n+1): od:seq(a(n),n=-1..40):od; # Richard Choulet, Jan 25 2010
  • Mathematica
    CoefficientList[Series[(2/(3*Sqrt[1-4*x]-1+4*x))*((1-Sqrt[1-4*x]) /(2*x))^(-1), {x, 0, 20}], x] (* Vaclav Kotesovec, Feb 13 2014 *)
    a[n_] := Binomial[2 n - 2, n] Hypergeometric2F1[1, 2 - n, n + 1, 1/2] / 2 + (-2)^(1 - n); Table[a[n], {n, 1, 26}] (* Peter Luschny, Dec 03 2021 *)
  • PARI
    a(n) = (-1)^n*sum(k=0, n, binomial(-n, k));
    vector(100, n, a(n-1)) \\ Altug Alkan, Oct 02 2015
    
  • Sage
    a=(x*(1+sqrt(1-4*x))/(sqrt(1-4*x)*(3-sqrt(1-4*x)))).series(x, 30).coefficients(x, sparse=False); a[1:] # G. C. Greubel, Feb 17 2019

Formula

If offset is 0, a(n) = Sum_{k=0..n} (-1)^(n-k)*binomial(n+k-1, k). - Vladeta Jovovic, Feb 18 2003
G.f.: x*(1-x*C)/(1-2*x*C)/(1+x*C), where C = (1-sqrt(1-4*x))/(2*x) is g.f. for Catalan numbers (A000108). - Vladeta Jovovic, Feb 18 2003
a(n) = Sum_{j=0..floor((n-1)/2)} binomial(2*n-2*j-4, n-3). - Emeric Deutsch, Jan 28 2004
a(n) = A108561(2*(n-1),n-1). - Reinhard Zumkeller, Jun 10 2005
a(n) = (-1)^n*Sum_{k=0..n} binomial(-n,k) (offset 0). - Paul Barry, Feb 17 2009
Other form of the G.f: f(z) = (2/(3*sqrt(1-4*z) -1 +4*z))*((1 -sqrt(1-4*z))/(2*z))^(-1). - Richard Choulet, Jan 25 2010
D-finite with recurrence 2*(-n+1)*a(n) + (9*n-17)*a(n-1) + (-3*n+19)*a(n-2) + 2*(-2*n+7)*a(n-3) = 0. - R. J. Mathar, Nov 30 2012
From Peter Bala, Oct 01 2015: (Start)
a(n) = [x^n] ((1 - x)^2/(1 - 2*x))^n.
Exp( Sum_{n >= 1} a(n+1)*x^n/n ) = 1 + x^2 + 2*x^3 + 6*x^4 + 18*x^5 + ... is the o.g.f for A000957. (End)
a(n) = binomial(2*n-2, n)*hypergeom([1, 2-n], [n+1], 1/2) / 2 + (-2)^(1-n). - Peter Luschny, Dec 03 2021
a(n) = 2 * A014301(n-1) for n>=3. - Alois P. Heinz, Dec 27 2023

Extensions

Corrected and extended by Vladeta Jovovic, Feb 17 2003

A108561 Triangle read by rows: T(n,0)=1, T(n,n)=(-1)^n, T(n+1,k)=T(n,k-1)+T(n,k) for 0 < k < n.

Original entry on oeis.org

1, 1, -1, 1, 0, 1, 1, 1, 1, -1, 1, 2, 2, 0, 1, 1, 3, 4, 2, 1, -1, 1, 4, 7, 6, 3, 0, 1, 1, 5, 11, 13, 9, 3, 1, -1, 1, 6, 16, 24, 22, 12, 4, 0, 1, 1, 7, 22, 40, 46, 34, 16, 4, 1, -1, 1, 8, 29, 62, 86, 80, 50, 20, 5, 0, 1, 1, 9, 37, 91, 148, 166, 130, 70, 25, 5, 1, -1, 1, 10, 46, 128, 239, 314, 296, 200, 95, 30, 6, 0, 1, 1, 11, 56, 174, 367
Offset: 0

Views

Author

Reinhard Zumkeller, Jun 10 2005

Keywords

Comments

Sum_{k=0..n} T(n,k) = A078008(n);
Sum_{k=0..n} abs(T(n,k)) = A052953(n-1) for n > 0;
T(n,1) = n - 2 for n > 1;
T(n,2) = A000124(n-3) for n > 2;
T(n,3) = A003600(n-4) for n > 4;
T(n,n-6) = A001753(n-6) for n > 6;
T(n,n-5) = A001752(n-5) for n > 5;
T(n,n-4) = A002623(n-4) for n > 4;
T(n,n-3) = A002620(n-1) for n > 3;
T(n,n-2) = A008619(n-2) for n > 2;
T(n,n-1) = n mod 2 for n > 0;
T(2*n,n) = A072547(n+1).
Sum_{k=0..n} T(n,k)*x^k = A232015(n), A078008(n), A000012(n), A040000(n), A001045(n+2), A140725(n+1) for x = 2, 1, 0, -1, -2, -3 respectively. - Philippe Deléham, Nov 17 2013, Nov 19 2013
(1,a^n) Pascal triangle with a = -1. - Philippe Deléham, Dec 27 2013
T(n,k) = A112465(n,n-k). - Reinhard Zumkeller, Jan 03 2014

Examples

			From _Philippe Deléham_, Nov 17 2013: (Start)
Triangle begins:
  1;
  1, -1;
  1,  0,  1;
  1,  1,  1, -1;
  1,  2,  2,  0,  1;
  1,  3,  4,  2,  1, -1;
  1,  4,  7,  6,  3,  0,  1; (End)
		

Crossrefs

Cf. A007318 (a=1), A008949(a=2), A164844(a=10).
Similar to the triangles A035317, A059259, A080242, A112555.
Cf. A072547 (central terms).

Programs

  • GAP
    Flat(List([0..13],n->List([0..n],k->Sum([0..k],i->Binomial(n,i)*(-2)^(k-i))))); # Muniru A Asiru, Feb 19 2018
  • Haskell
    a108561 n k = a108561_tabl !! n !! k
    a108561_row n = a108561_tabl !! n
    a108561_tabl = map reverse a112465_tabl
    -- Reinhard Zumkeller, Jan 03 2014
    
  • Maple
    A108561 := (n, k) -> add(binomial(n, i)*(-2)^(k-i), i = 0..k):
    seq(seq(A108561(n,k), k = 0..n), n = 0..12); # Peter Bala, Feb 18 2018
  • Mathematica
    Clear[t]; t[n_, 0] = 1; t[n_, n_] := t[n, n] = (-1)^Mod[n, 2]; t[n_, k_] := t[n, k] = t[n-1, k] + t[n-1, k-1]; Table[t[n, k], {n, 0, 13}, {k, 0, n}] // Flatten (* Jean-François Alcover, Mar 06 2013 *)
  • Sage
    def A108561_row(n):
        @cached_function
        def prec(n, k):
            if k==n: return 1
            if k==0: return 0
            return -prec(n-1,k-1)-sum(prec(n,k+i-1) for i in (2..n-k+1))
        return [(-1)^k*prec(n, k) for k in (1..n-1)]+[(-1)^(n+1)]
    for n in (1..12): print(A108561_row(n)) # Peter Luschny, Mar 16 2016
    

Formula

G.f.: (1-y*x)/(1-x-(y+y^2)*x). - Philippe Deléham, Nov 17 2013
T(n,k) = T(n-1,k) + T(n-2,k-1) + T(n-2,k-2), T(0,0)=T(1,0)=1, T(1,1)=-1, T(n,k)=0 if k < 0 or if k > n. - Philippe Deléham, Nov 17 2013
From Peter Bala, Feb 18 2018: (Start)
T(n,k) = Sum_{i = 0..k} binomial(n,i)*(-2)^(k-i), 0 <= k <= n.
The n-th row polynomial is the n-th degree Taylor polynomial of the rational function (1 + x)^n/(1 + 2*x) about 0. For example, for n = 4, (1 + x)^4/(1 + 2*x) = 1 + 2*x + 2*x^2 + x^4 + O(x^5). (End)

Extensions

Definition corrected by Philippe Deléham, Dec 26 2013

A001786 Expansion of 1/((1+x)*(1-x)^11).

Original entry on oeis.org

1, 10, 56, 230, 771, 2232, 5776, 13672, 30086, 62292, 122464, 230252, 416394, 727672, 1233584, 2035176, 3276559, 5159726, 7963384, 12066626, 17978389, 26373776, 38138464, 54422576, 76705564, 106873832, 147313024, 201017112, 271716644, 364028752, 483631776, 637467632, 833975341
Offset: 0

Views

Author

Keywords

Crossrefs

Cf. A001780, A158454 (signed column k=5).
Eleventh column of A112465.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50);
    Coefficients(R!( 1/((1+x)*(1-x)^11) )); // G. C. Greubel, Apr 20 2025
    
  • Mathematica
    CoefficientList[Series[1/((1+x)(1-x)^11),{x,0,50}],x] (* Vincenzo Librandi, Feb 24 2012 *)
    LinearRecurrence[{10,-44,110,-165,132,0,-132,165,-110,44,-10,1},{1,10,56,230,771,2232, 5776,13672,30086,62292,122464,230252},30] (* Harvey P. Dale, Oct 22 2015 *)
  • SageMath
    def A001786_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/((1+x)*(1-x)^11) ).list()
    print(A001786_list(50)) # G. C. Greubel, Apr 20 2025

Formula

Boas-Buck recurrence: a(n) = (1/n)*Sum_{p=0..n-1} (11 + (-1)^(n-p))*a(p), n >= 1, a(0) = 1. See the Boas-Buck comment in A046521 (here for the unsigned column k = 5 with offset 0). - Wolfdieter Lang, Aug 10 2017

A001781 Expansion of 1/((1+x)*(1-x)^10).

Original entry on oeis.org

1, 9, 46, 174, 541, 1461, 3544, 7896, 16414, 32206, 60172, 107788, 186142, 311278, 505912, 801592, 1241383, 1883167, 2803658, 4103242, 5911763, 8395387, 11764688, 16284112, 22282988, 30168268, 40439192, 53704088, 70699532, 92312108, 119603024, 153835856, 196507709, 249384101
Offset: 0

Views

Author

Keywords

Crossrefs

Cf. A000582.
Tenth column of A112465.

Programs

  • Magma
    [1/2903040*(2*n+11) *(2*n^8 +88*n^7 +1616*n^6 +16060*n^5 +93656*n^4 +324808*n^3 +646236*n^2 +663894*n +263655)+(-1)^n/1024  : n in [0..30]]; // Vincenzo Librandi, Oct 08 2011
    
  • Magma
    R:=PowerSeriesRing(Integers(), 50);
    Coefficients(R!( 1/((1+x)*(1-x)^10) )); // G. C. Greubel, Apr 20 2025
    
  • Maple
    A001781 := proc(n) 1/2903040*(2*n+11) *(2*n^8 +88*n^7 +1616*n^6 +16060*n^5 +93656*n^4 +324808*n^3 +646236*n^2 +663894*n +263655)+(-1)^n/1024 ; end proc:
    seq(A001781(n),n=0..50) ; # R. J. Mathar, Mar 22 2011
  • PARI
    Vec(1/(1+x)/(1-x)^10+O(x^99)) \\ Charles R Greathouse IV, Apr 18 2012
    
  • SageMath
    def A001781_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/((1+x)*(1-x)^10) ).list()
    print(A001781_list(50)) # G. C. Greubel, Apr 20 2025

Formula

a(n) = +9*a(n-1) -35*a(n-2) +75*a(n-3) -90*a(n-4) +42*a(n-5) +42*a(n-6) -90*a(n-7) +75*a(n-8) -35*a(n-9) +9*a(n-10) -a(n-11). - R. J. Mathar, Mar 22 2011
a(n) + a(n+1) = A000582(n+10). - R. J. Mathar, Jan 06 2021

A001808 Expansion of 1/((1+x)*(1-x)^12).

Original entry on oeis.org

1, 11, 67, 297, 1068, 3300, 9076, 22748, 52834, 115126, 237590, 467842, 884236, 1611908, 2845492, 4880668, 8157227, 13316953, 21280337, 33346963, 51325352, 77699128, 115837592, 170260168, 246965732, 353839564, 501152588, 702169700, 973886344, 1337915096
Offset: 0

Views

Author

Keywords

Crossrefs

Twelfth column of A112465.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 50);
    Coefficients(R!( 1/((1+x)*(1-x)^12) )); // G. C. Greubel, Apr 20 2025
    
  • Mathematica
    CoefficientList[Series[1/((1+x)(1-x)^12),{x,0,50}],x] (* Vincenzo Librandi, Feb 24 2012 *)
    LinearRecurrence[{11,-54,154,-275,297,-132,-132,297,-275,154,-54,11,-1},{1,11,67,297,1068,3300,9076,22748,52834,115126,237590,467842,884236},30] (* Harvey P. Dale, Jun 22 2014 *)
  • PARI
    Vec(1/((1+x)*(1-x)^12)+O(x^20)) \\ Edward Jiang, Sep 07 2014
    
  • SageMath
    def A001808_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/((1+x)*(1-x)^12) ).list()
    print(A001808_list(50)) # G. C. Greubel, Apr 20 2025

A112466 Riordan array ((1+2*x)/(1+x), x/(1+x)).

Original entry on oeis.org

1, 1, 1, -1, 0, 1, 1, -1, -1, 1, -1, 2, 0, -2, 1, 1, -3, 2, 2, -3, 1, -1, 4, -5, 0, 5, -4, 1, 1, -5, 9, -5, -5, 9, -5, 1, -1, 6, -14, 14, 0, -14, 14, -6, 1, 1, -7, 20, -28, 14, 14, -28, 20, -7, 1, -1, 8, -27, 48, -42, 0, 42, -48, 27, -8, 1, 1, -9, 35, -75, 90, -42, -42, 90, -75, 35, -9, 1, -1, 10, -44, 110, -165, 132, 0, -132, 165, -110, 44, -10, 1
Offset: 0

Views

Author

Paul Barry, Sep 06 2005

Keywords

Comments

Inverse is A112465.
Triangle T(n,k), 0 <= k <= n, read by rows, given by [1, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938. - Philippe Deléham, Aug 07 2006; corrected by Philippe Deléham, Dec 11 2008
Equals A097808 when the first column is removed. - Georg Fischer, Jul 26 2023

Examples

			Triangle starts
   1;
   1,  1;
  -1,  0,  1;
   1, -1, -1,  1;
  -1,  2,  0, -2,  1;
   1, -3,  2,  2, -3,  1;
  -1,  4, -5,  0,  5, -4,  1;
From _Paul Barry_, Apr 08 2011: (Start)
Production matrix begins
   1,  1;
  -2, -1,  1;
   2,  0, -1,  1;
  -2,  0,  0, -1,  1;
   2,  0,  0,  0, -1,  1;
  -2,  0,  0,  0,  0, -1,  1;
   2,  0,  0,  0,  0,  0, -1,  1; (End)
		

Crossrefs

Columns: A248157(n+2) (k=1), (-1)^n*A080956(n-2) (k=2), (-1)^(n-1)*A254749(n-2) (k=3).

Programs

  • Magma
    A112466:= func< n,k | n eq 0 select 1 else (-1)^(n+k)*(Binomial(n,k) - 2*Binomial(n-1,k)) >;
    [A112466(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Apr 30 2025
    
  • Maple
    seq(seq( (-1)^(n-k)*(2*binomial(n-1, k-1)-binomial(n, k)), k=0..n), n=0..10); # G. C. Greubel, Feb 19 2020
  • Mathematica
    {1}~Join~Table[(Binomial[n, n - k] - 2 Binomial[n - 1, n - k - 1])*(-1)^(n - k), {n, 12}, {k, 0, n}] // Flatten (* Michael De Vlieger, Feb 18 2020 *)
  • PARI
    T(n,k) = (-1)^(n-k)*(binomial(n, n-k) - 2*binomial(n-1, n-k-1)); \\ Michel Marcus, Feb 19 2020
    
  • SageMath
    def A112466(n,k): return 1 if (n==0) else (-1)^(n+k)*(binomial(n,k) - 2*binomial(n-1,k))
    print(flatten([[A112466(n,k) for k in range(n+1)] for n in range(13)])) # G. C. Greubel, Apr 30 2025

Formula

Number triangle: T(n,k) = (-1)^(n-k)*(C(n, n-k) - 2*C(n-1, n-k-1)), with T(0,0) = 1.
T(2*n, n) = 0 (main diagonal).
Sum_{k=0..n} T(n, k) = 0 + [n=0] + 2*[n=1] (row sums).
Sum_{k=0..floor(n/2)} T(n-k, k) = (-1)^(n+1)*Fibonacci(n-2) (diagonal sums).
Sum_{k=0..n} T(n,k)*x^k = (x+1)*(x-1)^(n-1), for n >= 1. - Philippe Deléham, Oct 03 2005
T(0,0) = T(1,0) = T(1,1) = 1, T(n,k) = 0 if n < 0 or if n < k, T(n,k) = T(n-1,k-1) - T(n-1,k) for n > 1. - Philippe Deléham, Nov 26 2006
G.f.: (1+2*x)/(1+x-x*y). - R. J. Mathar, Aug 11 2015
From G. C. Greubel, Apr 30 2025: (Start)
T(2*n+1, 2*n+1-k) = T(2*n+1, k) (symmetric odd n rows).
T(2*n, 2*n-k) = (-1)*T(2*n, k) (antisymmetric even n rows).
Sum_{k=0..n} (-1)^k*T(n, k) = A000007(n) (signed row sums).
Sum_{k=0..floor(n/2)} (-1)^k*T(n-k, k) = (-1)^n*A057079(n+2) (signed diagonal sums). (End)
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