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.

Previous Showing 21-27 of 27 results.

A029618 Numbers in (3,2)-Pascal triangle (by row).

Original entry on oeis.org

1, 3, 2, 3, 5, 2, 3, 8, 7, 2, 3, 11, 15, 9, 2, 3, 14, 26, 24, 11, 2, 3, 17, 40, 50, 35, 13, 2, 3, 20, 57, 90, 85, 48, 15, 2, 3, 23, 77, 147, 175, 133, 63, 17, 2, 3, 26, 100, 224, 322, 308, 196, 80, 19, 2, 3, 29, 126, 324, 546, 630, 504, 276, 99, 21, 2, 3, 32, 155, 450, 870
Offset: 0

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Author

Keywords

Comments

Reverse of A029600. - Philippe Deléham, Nov 21 2006
Triangle T(n,k), read by rows, given by (3,-2,0,0,0,0,0,0,0,...) DELTA (2,-1,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938. - Philippe Deléham, Oct 10 2011
Row n: expansion of (3+2x)*(1+x)^(n-1), n>0. - Philippe Deléham, Oct 10 2011
For a closed-form formula for generalized Pascal's triangle see A228576. - Boris Putievskiy, Sep 04 2013

Examples

			Triangle begins as:
  1;
  3,  2;
  3,  5,  2;
  3,  8,  7,  2;
  3, 11, 15,  9,  2;
  ...
		

Crossrefs

Cf. A007318, A029600, A084938, A228196, A228576, A016789 (2nd column), A005449 (3rd column), A006002 (4th column).

Programs

  • GAP
    T:= function(n,k)
        if n=0 and k=0 then return 1;
        elif k=0 then return 3;
        elif k=n then return 2;
        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 12 2019
  • Maple
    A029618 := proc(n,k)
        if k < 0 or k > n then
            0;
        elif  n = 0 then
            1;
        elif k=0 then
            3;
        elif k = n then
            2;
        else
            procname(n-1,k-1)+procname(n-1,k) ;
        end if;
    end proc: # R. J. Mathar, Jul 08 2015
  • Mathematica
    T[n_, k_]:= T[n, k]= If[n==0 && k==0, 1, If[k==0, 3, If[k==n, 2, T[n-1, k-1] + T[n-1, k] ]]]; Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Nov 13 2019 *)
  • PARI
    T(n,k) = if(n==0 && k==0, 1, if(k==0, 3, if(k==n, 2, T(n-1, k-1) + T(n-1, k) ))); \\ G. C. Greubel, Nov 12 2019
    
  • Sage
    @CachedFunction
    def T(n, k):
        if (n==0 and k==0): return 1
        elif (k==0): return 3
        elif (k==n): return 2
        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 12 2019
    

Formula

T(n,k) = T(n-1,k-1) + T(n-1,k) with T(0,0)=1, T(n,0)=3, T(n,n)=2; n, k > 0. - Boris Putievskiy, Sep 04 2013
G.f.: (-1-x*y-2*x)/(-1+x*y+x). - R. J. Mathar, Aug 11 2015

A095666 Pascal (1,4) triangle.

Original entry on oeis.org

4, 1, 4, 1, 5, 4, 1, 6, 9, 4, 1, 7, 15, 13, 4, 1, 8, 22, 28, 17, 4, 1, 9, 30, 50, 45, 21, 4, 1, 10, 39, 80, 95, 66, 25, 4, 1, 11, 49, 119, 175, 161, 91, 29, 4, 1, 12, 60, 168, 294, 336, 252, 120, 33, 4, 1, 13, 72, 228, 462, 630, 588, 372, 153, 37, 4, 1, 14, 85, 300, 690, 1092
Offset: 0

Views

Author

Wolfdieter Lang, Jun 11 2004

Keywords

Comments

This is the fourth member, q=4, in the family of (1,q) Pascal triangles: A007318 (Pascal (q=1)), A029635 (q=2) (but with a(0,0)=2, not 1), A095660 (q=3), A096940 (q=5), A096956 (q=6).
This is an example of a Riordan triangle (see A053121 for a comment and the 1991 Shapiro et al. reference on the Riordan group) with o.g.f. of column no. m of the type g(x)*(x*f(x))^m with f(0)=1. Therefore the o.g.f. for the row polynomials p(n,x) := Sum_{m=0..n} a(n,m)*x^m is G(z,x) = g(z)/(1 - x*z*f(z)). Here: g(x) = (4-3*x)/(1-x), f(x) = 1/(1-x), hence G(z,x) = (4-3*z)/(1-(1+x)*z).
The SW-NE diagonals give Sum_{k=0..ceiling((n-1)/2)} a(n-1-k, k) = A022095(n-2), n >= 2, with n=1 value 4. [Observation by Paul Barry, Apr 29 2004. Proof via recursion relations and comparison of inputs.]
T(2*n,n) = A029609(n) for n > 0, A029609 are the central terms of the Pascal (2,3) triangle A029600. - Reinhard Zumkeller, Apr 08 2012

Examples

			Triangle begins:
  [4];
  [1,4];
  [1,5,4];
  [1,6,9,4];
  [1,7,15,13,4];
  ...
		

Crossrefs

Row sums: A020714(n-1), n >= 1, 4 if n=0.
Alternating row sums are [4, -3, followed by 0's].
Column sequences (without leading zeros) give for m=1..9, with n >= 0: A000027(n+4), A055999(n+1), A060488(n+3), A095667-71, A095819.

Programs

  • Haskell
    a095666 n k = a095666_tabl !! n !! k
    a095666_row n = a095666_tabl !! n
    a095666_tabl = [4] : iterate
       (\row -> zipWith (+) ([0] ++ row) (row ++ [0])) [1,4]
    -- Reinhard Zumkeller, Apr 08 2012
  • Maple
    a(n,k):=(1+3*k/n)*binomial(n,k) # Mircea Merca, Apr 08 2012
  • Mathematica
    A095666[n_, k_] := If[n == k,  4, (3*k/n + 1)*Binomial[n, k]];
    Table[A095666[n, k], {n, 0, 12}, {k, 0, n}] (* Paolo Xausa, Apr 14 2025 *)

Formula

Recursion: a(n, m) = 0 if m > n, a(0, 0) = 4; a(n, 0) = 1 if n>=1; a(n, m) = a(n-1, m) + a(n-1, m-1).
G.f. column m (without leading zeros): (4-3*x)/(1-x)^(m+1), m >= 0.
a(n,k) = (1 + 3*k/n)*binomial(n,k). - Mircea Merca, Apr 08 2012

A051432 (Terms in A029617)/2.

Original entry on oeis.org

4, 13, 7, 20, 45, 10, 161, 112, 50, 13, 273, 162, 63, 588, 435, 225, 16, 1023, 660, 2178, 1683, 396, 111, 19, 3861, 507, 130, 8151, 4004, 637, 22, 30745, 25168, 16380, 8372, 3290, 960, 196, 25, 55913, 41548, 24752, 11662, 4250, 1156, 221, 116688, 97461
Offset: 0

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Keywords

Crossrefs

A051433 (Terms in A029605)/2.

Original entry on oeis.org

1, 1, 1, 4, 1, 1, 12, 13, 7, 1, 25, 20, 1, 24, 45, 10, 1, 1, 40, 98, 154, 161, 112, 50, 13, 1, 138, 252, 315, 273, 162, 63, 1, 60, 390, 567, 588, 435, 225, 16, 1, 957, 1155, 1023, 660, 1, 84, 319, 825, 2112, 2178, 1683, 396, 111, 19, 1, 403, 1144, 4290, 3861, 507
Offset: 0

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Author

Keywords

Crossrefs

A051434 (Terms in A029607)/2.

Original entry on oeis.org

4, 12, 13, 7, 25, 20, 24, 45, 10, 40, 98, 154, 161, 112, 50, 13, 138, 252, 315, 273, 162, 63, 60, 390, 567, 588, 435, 225, 16, 957, 1155, 1023, 660, 84, 319, 825, 2112, 2178, 1683, 396, 111, 19, 403, 1144, 4290, 3861, 507, 130, 112, 1547, 6006, 8151, 4004
Offset: 0

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Author

Keywords

Crossrefs

A051435 (Terms in A029613)/2.

Original entry on oeis.org

12, 24, 40, 98, 154, 138, 252, 60, 390, 567, 957, 84, 319, 825, 2112, 403, 1144, 112, 1547, 6006, 144, 740, 2660, 7098, 14560, 23452, 30030, 884, 3400, 9758, 21658, 38012, 53482, 180, 4284, 13158, 31416, 59670, 91494, 114257, 17442, 44574, 91086
Offset: 0

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Author

Keywords

Crossrefs

A239310 Numbers of the form A001700(n)*k, n>=1, k>=2.

Original entry on oeis.org

6, 9, 12, 15, 18, 20, 21, 24, 27, 30, 33, 36, 39, 40, 42, 45, 48, 50, 51, 54, 57, 60, 63, 66, 69, 70, 72, 75, 78, 80, 81, 84, 87, 90, 93, 96, 99, 100, 102, 105, 108, 110, 111, 114, 117, 120, 123, 126, 129, 130, 132, 135, 138, 140, 141, 144, 147
Offset: 1

Views

Author

Bob Selcoe, Mar 31 2016

Keywords

Comments

Numbers that are central coefficients T(2k,k) k>=2 in (a,b)-Pascal triangles, where (a,b) represent boundary conditions; i.e., T(2k,k) = (a+b)*A001700(k-1).

Examples

			a(n)=50 appears because A001700(2)=10, so T(6,3)=50 in (1,4)- and (2,3)-Pascal triangles.
		

Crossrefs

Cf. A001700.
Cf. A007318 (Pascal's triangle), A029600 ((2,3)-Pascal triangle), A095666 ((1,4)-Pascal triangle).

Programs

  • PARI
    is(n)=my(k=1,t=3); while(n>=2*t, if(n%t==0, return(1)); k++; t=binomial(2*k+1, k+1)); 0 \\ Charles R Greathouse IV, Apr 04 2016

Formula

a(n) ~ kn, where k = 2.441823902640895564.... (This constant exists since A001700 grows exponentially.) - Charles R Greathouse IV, Apr 04 2016
Previous Showing 21-27 of 27 results.