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 1-2 of 2 results.

A132730 Row sums of triangle A132729.

Original entry on oeis.org

1, 2, 3, 8, 21, 50, 111, 236, 489, 998, 2019, 4064, 8157, 16346, 32727, 65492, 131025, 262094, 524235, 1048520, 2097093, 4194242, 8388543, 16777148, 33554361, 67108790, 134217651, 268435376, 536870829
Offset: 0

Views

Author

Gary W. Adamson, Aug 26 2007

Keywords

Examples

			a(4) = 21 = sum of row 4 terms of triangle A132729: (1 + 5 + 9 + 5 + 1).
a(3) = 8 = (1, 3, 3, 1) dot (1, 1, 0, 4) = (1 + 3 + 0 + 4).
		

Crossrefs

Cf. A132729.

Programs

  • Magma
    [1] cat [2^(n+1) -3*n +1: n in [0..30]]; // G. C. Greubel, Feb 14 2021
  • Mathematica
    LinearRecurrence[{4,-5,2},{1,2,3,8},30] (* Harvey P. Dale, Dec 30 2015 *)
    Table[2^(n+1) -3*n +1 -2*Boole[n==0], {n,0,30}] (* G. C. Greubel, Feb 14 2021 *)
  • Sage
    [1]+[2^(n+1) -3*n +1 for n in (1..30)] # G. C. Greubel, Feb 14 2021
    

Formula

Binomial transform of [1, 1, 0, 4, 0, 4, 0, 4, ...].
a(n) = 2^(n+1) - 3*n + 1, for n > 0. - R. J. Mathar, Apr 04 2012
From G. C. Greubel, Feb 14 2021: (Start)
G.f.: (1 - 2*x + 4*x^3)/((1-x)^2 * (1-2*x)).
E.g.f.: -2 + (1-3*x)*exp(x) + 2*exp(2*x). (End)

A132737 Triangle T(n,k) = 2*binomial(n,k) + 1, read by rows.

Original entry on oeis.org

1, 1, 1, 1, 5, 1, 1, 7, 7, 1, 1, 9, 13, 9, 1, 1, 11, 21, 21, 11, 1, 1, 13, 31, 41, 31, 13, 1, 1, 15, 43, 71, 71, 43, 15, 1, 1, 17, 57, 113, 141, 113, 57, 17, 1, 1, 19, 73, 169, 253, 253, 169, 73, 19, 1, 1, 21, 91, 241, 421, 505, 421, 241, 91, 21, 1, 1, 23, 111, 331, 661, 925, 925, 661, 331, 111, 23, 1
Offset: 0

Views

Author

Gary W. Adamson, Aug 26 2007

Keywords

Examples

			First few rows of the triangle are:
  1;
  1,  1;
  1,  5,  1;
  1,  7,  7,  1;
  1,  9, 13,  9,  1;
  1, 11, 21, 21, 11,  1;
  1, 13, 31, 41, 31, 13,  1;
  1, 15, 43, 71, 71, 43, 15, 1;
  ...
		

Crossrefs

Sequences of the form 2*binomial(n,k) + q: A132729 (q=-3), A132731 (q=-2), A109128 (q=-1), A132046 (q=0), this sequence (q=1).

Programs

  • Magma
    A132737:= func< n,k | k eq 0 or k eq n select 1 else 2*Binomial(n,k) +1 >;
    [A132737(n,k): k in [0..n], n in [0..15]]; // G. C. Greubel, Feb 15 2021
  • Mathematica
    T[n_, k_]:= If[k==0 || k==n, 1, 2*Binomial[n,k] +1];
    Table[T[n, k], {n,0,15}, {k,0,n}]//Flatten (* G. C. Greubel, Feb 15 2021 *)
  • Sage
    def A132737(n,k): return 1 if (k==0 or k==n) else 2*binomial(n,k) + 1
    flatten([[A132737(n,k) for k in (0..n)] for n in (0..15)]) # G. C. Greubel, Feb 15 2021
    

Formula

T(n, k) = 2*A132735(n, k) - 1, an infinite lower triangular matrix.
T(n,0) = T(n,n) = 1; otherwise T(n,k) = 2*C(n,k) + 1. - Franklin T. Adams-Watters, Jul 06 2009
Sum_{k=0..n} T(n, k) = 2^(n+1) + n - 3 + 2*[n=0] = A132738(n). - G. C. Greubel, Feb 15 2021

Extensions

Extended by Franklin T. Adams-Watters, Jul 06 2009
Showing 1-2 of 2 results.