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 1-3 of 3 results.

A114202 A Pascal-Jacobsthal triangle.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 8, 4, 1, 1, 5, 16, 16, 5, 1, 1, 6, 27, 42, 27, 6, 1, 1, 7, 41, 87, 87, 41, 7, 1, 1, 8, 58, 156, 216, 156, 58, 8, 1, 1, 9, 78, 254, 456, 456, 254, 78, 9, 1, 1, 10, 101, 386, 860, 1122, 860, 386, 101, 10, 1
Offset: 0

Views

Author

Paul Barry, Nov 16 2005

Keywords

Comments

Row sums are A114203. T(2n,n) is A114204. Inverse has row sums 0^n.

Examples

			Triangle begins
  1;
  1, 1;
  1, 2,  1;
  1, 3,  3,  1;
  1, 4,  8,  4,  1;
  1, 5, 16, 16,  5,  1;
  1, 6, 27, 42, 27,  6, 1;
  1, 7, 41, 87, 87, 41, 7, 1;
  ...
		

Formula

As a number triangle, with J(n) = A001045(n):
T(n, k) = Sum_{i=0..n-k} C(n-k, i)*C(k, i)*J(i);
T(n, k) = Sum_{i=0..n} C(n-k, n-i)*C(k, i-k)*J(i-k);
T(n, k) = Sum_{i=0..n} C(k, i)*C(n-k, n-i)*J(k-i) if k <= n, and 0 otherwise.
As a square array, with J(n) = A001045(n):
T(n, k) = Sum_{i=0..n} C(n, i)C(k, i)*J(i);
T(n, k) = Sum_{i=0..n+k} C(n, n+k-i)*C(k, i-k)*J(i-k);
Column k has g.f. (Sum_{i=0..k} C(k, i)*J(i+1)*(x/(1 - x))^i)*x^k/(1 - x).

A373358 a(n) = 4*a(n-1) -5*a(n-2) +2*a(n-3) +2*a(n-4) for a(0) = a(1) = 0, a(2) = 1, a(3) = 4 for n >= 4.

Original entry on oeis.org

0, 0, 1, 4, 11, 26, 59, 136, 323, 782, 1903, 4620, 11175, 26970, 65051, 156944, 378811, 914566, 2208199, 5331476, 12871663, 31074802, 75020243, 181113240, 437244675, 1055602590, 2548453951, 6152518684, 14853499511, 35859517706, 86572518539, 209004522016, 504581529803, 1218167581622
Offset: 0

Views

Author

Paul Curtz, Jun 02 2024

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{4, -5, 2, 2}, {0, 0, 1, 4}, 50] (* Paolo Xausa, Jun 19 2024 *)
    nxt[{a_,b_,c_,d_}]:={b,c,d,4d-5c+2b+2a}; NestList[nxt,{0,0,1,4},40][[;;,1]] (* Harvey P. Dale, Jan 11 2025 *)
  • PARI
    a(n) = ((([2, 1; 1, 0]^(n+1))[2, 1]) - (1+I)^(n-1) - (1-I)^(n-1))/3 \\ Thomas Scheuerle, Jun 03 2024

Formula

G.f.: x^2 / ( (1 - 2*x - x^2) * (1 - 2*x + 2*x^2) ).
E.g.f.: exp(x)*(2*cosh(sqrt(2)*x) - 2*(cos(x)+sin(x)) + sqrt(2)*sinh(sqrt(2)*x))/6.
a(n) = A373245(n+1) - A114203(n+1).
a(0) = 0, a(n) = A373245(n-1) + A146559(n-1).
Binomial transform of 0, 0, followed by A077893 = abs(A077953) = abs(A077980).
a(n) = 4*a(n-1) -5*a(n-2) +2*a(n-3) +2*a(n-4) for n >= 4.
From Thomas Scheuerle, Jun 03 2024: (Start)
a(n) = (A000129(n+1) - A009545(n+1))/3.
a(n) = (-i*sqrt(2)*(1-i)^(n+1) + i*sqrt(2)*(1+i)^(n+1) - (1-sqrt(2))^(n+1) + (1+sqrt(2))^(n+1))/(6*sqrt(2)).
a(n) = 2^n*(hypergeom([1/2 - n/2, -n/2], [-n], -1) - hypergeom([1/2 - n/2, -n/2], [-n], 2))/3. (End)

A373245 Binomial transform of A135318.

Original entry on oeis.org

1, 2, 4, 9, 22, 55, 136, 331, 798, 1919, 4620, 11143, 26906, 64987, 156944, 378939, 914822, 2208455, 5331476, 12871151, 31073778, 75019219, 181113240, 437246723, 1055606686, 2548458047, 6152518684, 14853491319, 35859501322, 86572502155, 209004522016
Offset: 0

Views

Author

Paul Curtz, May 29 2024

Keywords

Crossrefs

Cf. A135318.
Cf. A114203.

Programs

  • Mathematica
    CoefficientList[Series[(1 - 2*x + x^2 + x^3)/((1 - 2*x - x^2)*(1 - 2*x + 2*x^2)), {x, 0, 30}], x] (* Vaclav Kotesovec, May 29 2024 *)

Formula

G.f.: (1 - 2*x + x^2 + x^3)/((1 - 2*x - x^2)*(1 - 2*x + 2*x^2)). - Vaclav Kotesovec, May 29 2024
a(n) = A114203(n+1)/2. - Hugo Pfoertner, May 29 2024
E.g.f.: exp(x)*(2*cos(x) + 4*cosh(sqrt(2)*x) + 3*sqrt(2)*sinh(sqrt(2)*x))/6. - Stefano Spezia, May 29 2024

Extensions

More terms from Vaclav Kotesovec, May 29 2024
Showing 1-3 of 3 results.