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.

A339493 a(n) = A333650(n, 3) for n >= 3; a(1) = a(2) = 0.

Original entry on oeis.org

0, 0, 4, 11, 24, 52, 110, 228, 467, 949, 1916, 3848, 7696, 15342, 30505, 60527, 119892, 237156, 468590, 925032, 1824727, 3597289, 7088216, 13961168, 27489168, 54110618, 106489245, 209531251, 412217072, 810865812, 1594878078, 3136673996, 6168522827, 12130206941
Offset: 1

Views

Author

Peter Luschny, Dec 07 2020

Keywords

Crossrefs

A339346 a(n) is the number of domino towers of height n consisting of 2*n bricks, a(n) = A333650(2*n, n).

Original entry on oeis.org

1, 4, 24, 168, 1257, 9778, 77994, 633056, 5204434
Offset: 1

Views

Author

Peter Luschny, Dec 01 2020

Keywords

Crossrefs

Cf. A333650.

A339494 T(n, k) is the number of domino towers of n bricks with height at most 3 and k bricks in the base floor. Triangle read by rows, T(n, k) for 1 <= k <= n.

Original entry on oeis.org

1, 2, 1, 5, 3, 1, 5, 9, 4, 1, 3, 14, 14, 5, 1, 1, 16, 29, 20, 6, 1, 0, 12, 46, 51, 27, 7, 1, 0, 5, 52, 101, 81, 35, 8, 1, 0, 1, 41, 150, 190, 120, 44, 9, 1, 0, 0, 22, 169, 345, 323, 169, 54, 10, 1, 0, 0, 7, 143, 495, 687, 511, 229, 65, 11, 1
Offset: 1

Views

Author

Peter Luschny, Dec 07 2020

Keywords

Comments

This is the third triangle in a sequence of triangles: The first is the unit triangle A023531; the second is the binomial triangle C(k, n-k) without the first column, triangle A030528. This triangle highlights the connection between the Pascal triangle and the Fibonacci numbers in the case m = 2. Similarly, the current triangle and its row sums generalizes this to the case m = 3 of the construction of Union(A333650(n, j), j=1..m), classified by the number of bricks in the base floor.

Examples

			Triangle starts:        n: [row] sum
                          1: [1] 1
                         2: [2, 1] 3
                       3: [5, 3, 1] 9
                     4: [5, 9, 4, 1] 19
                   5: [3, 14, 14, 5, 1] 37
                 6: [1, 16, 29, 20, 6, 1] 73
              7: [0, 12, 46, 51, 27, 7, 1] 144
            8: [0, 5, 52, 101, 81, 35, 8, 1] 283
         9: [0, 1, 41, 150, 190, 120, 44, 9, 1] 556
     10: [0, 0, 22, 169, 345, 323, 169, 54, 10, 1] 1093
		

Crossrefs

Cf. A339495 (row sums), A333650, A030528, A023531.

A339029 Expansion of (1 + 4*x - 20*x^2 + 8*x^3 + 33*x^4 - 4*x^5 - 33*x^6)/(1 - 2*x)^4.

Original entry on oeis.org

1, 12, 52, 168, 497, 1412, 3879, 10360, 27016, 69024, 173264, 428288, 1044480, 2516992, 6001408, 14174208, 33191936, 77127680, 177967104, 408027136, 930021376, 2108424192, 4756275200, 10680270848, 23880794112, 53185871872, 118016180224, 260969594880, 575223627776
Offset: 0

Views

Author

Peter Luschny, Dec 01 2020

Keywords

Crossrefs

Cf. A339252 (k=2), A339254 (k=3), A333650.

Programs

  • Maple
    gf := (1 + 4*x - 20*x^2 + 8*x^3 + 33*x^4 - 4*x^5 - 33*x^6)/(1 - 2*x)^4:
    ser := series(gf, x, 32): seq(coeff(ser, x, n), n = 0..28);
  • Mathematica
    LinearRecurrence[{8, -24, 32, -16}, {1, 12, 52, 168, 497, 1412, 3879}, 30] (* Paolo Xausa, Feb 01 2024 *)

Formula

a(n) = 2^(n-7)*(588 + 367*n + 84*n^2 + 9*n^3) for n >= 3.

A339495 Row sums of A339494.

Original entry on oeis.org

1, 3, 9, 19, 37, 73, 144, 283, 556, 1093, 2149, 4225, 8306, 16329, 32102, 63111, 124073, 243921, 479536, 942743, 1853384, 3643657, 7163241, 14082561, 27685586, 54428429, 107003474, 210363291, 413563341, 813044121, 1598402656, 3142376883, 6177750292, 12145137293
Offset: 1

Views

Author

Peter Luschny, Dec 07 2020

Keywords

Crossrefs

Formula

a(n) = A339493(n) + Fibonacci(n + 2) for n >= 2.
a(n) = [x^n] -x*(x*(x + 1)*(x*(x*(x*(x*(x + 2) + 2) + 3) + 3) + 2) + 1)/(x^5 + x^4 + x^3 + x^2 + x - 1).
Showing 1-5 of 5 results.