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.

A288836 a(n) = (1/3!)*3^(n+1)*(n+5)*(n+1)*(n).

Original entry on oeis.org

18, 189, 1296, 7290, 36450, 168399, 734832, 3070548, 12400290, 48715425, 187067232, 704690766, 2611501074, 9542023155, 34437376800, 122941435176, 434685788658, 1523724783237, 5299912289520, 18305618105250, 62824881337218, 214364018189079, 727538485975056
Offset: 1

Views

Author

Gregory Gerard Wojnar, Jun 17 2017

Keywords

Crossrefs

Column k=6 of A287768.

Programs

  • Mathematica
    LinearRecurrence[{12,-54,108,-81},{18,189,1296,7290},30] (* Harvey P. Dale, May 09 2025 *)

Formula

O.g.f.: z*3^2*(2-3*z)/(1-3*z)^4.
a(n) = -A287768(n+5,6).

A288838 a(n) = (1/4!)*3^(n+2)*(n+7)*(n+2)*(n+1)*(n).

Original entry on oeis.org

54, 729, 6075, 40095, 229635, 1194102, 5786802, 26572050, 116917020, 496897335, 2051893701, 8269753401, 32643763425, 126557359740, 482984209620, 1817776934388, 6757388169138, 24843338857125, 90429753439935, 326206114635555, 1167092987918319, 4144371018322194
Offset: 1

Views

Author

Gregory Gerard Wojnar, Jun 17 2017

Keywords

Crossrefs

Column k=9 of A287768.

Programs

  • Mathematica
    Table[1/4! 3^(n+2) (n+7)(n+2)(n+1)n,{n,30}] (* or *) LinearRecurrence[{15,-90,270,-405,243},{54,729,6075,40095,229635},30] (* Harvey P. Dale, May 15 2022 *)
  • PARI
    a(n)=3^n*3*n*(n+1)*(n+2)*(n+7)/8 \\ Charles R Greathouse IV, Jun 19 2017

Formula

O.g.f.: z*3^3*(2-3*z)/(1-3*z)^5.
a(n) = A287768(n+7,9).

A288842 Triangle (sans apex) of coefficients of terms of the form (eM_1)^j*(eM_2)^k re construction of triangle A287768.

Original entry on oeis.org

1, 2, 3, 9, 6, 9, 36, 45, 18, 27, 135, 243, 189, 54, 81, 486, 1134, 1296, 729, 162, 243, 1701, 4860, 7290, 6075, 2673, 486, 729, 5832, 19683, 36450, 40095, 26244, 9477, 1458, 2187, 19683, 76545, 168399, 229635, 199017, 107163, 32805, 4374, 6561, 65610, 288684, 734832, 1194102, 1285956, 918540, 419904, 111537, 13122
Offset: 1

Views

Author

Gregory Gerard Wojnar, Jun 17 2017

Keywords

Examples

			Triangle begins:
  1,  2;
  3,  9,  6;
  9, 36, 45, 18;
		

Crossrefs

Columns are: A000244, A288834, A288835, A288836, A288838, etc.
Cf. A287768.

Programs

  • Mathematica
    T[1, 1] = 1; T[1, 2] = 2;
    T[n_, k_] /; 1 <= k <= n+1 := T[n, k] = 3 T[n-1, k-1] + 3 T[n-1, k];
    T[, ] = 0;
    Table[T[n, k], {n, 1, 9}, {k, 1, n+1}] // Flatten (* Jean-François Alcover, Nov 16 2018 *)

Formula

T(n+1,k+1) = 3*T(n,k) + 3*T(n,k+1).
Showing 1-3 of 3 results.