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.

A257614 Triangle read by rows: T(n, k) = t(n-k, k), where t(0,0) = 1, t(n,m) = 0 if n < 0 or m < 0, else t(n,m) = f(m)*t(n-1,m) + f(n)*t(n,m-1), and f(n) = 5*n + 2.

Original entry on oeis.org

1, 2, 2, 4, 28, 4, 8, 244, 244, 8, 16, 1844, 5856, 1844, 16, 32, 13260, 101620, 101620, 13260, 32, 64, 93684, 1511160, 3455080, 1511160, 93684, 64, 128, 657836, 20663388, 91981880, 91981880, 20663388, 657836, 128, 256, 4609588, 269011408, 2121603436, 4047202720, 2121603436, 269011408, 4609588, 256
Offset: 0

Views

Author

Dale Gerdemann, May 09 2015

Keywords

Examples

			Array t(n,k) begins as:
   1,      2,         4,           8,            16, ... A000079;
   2,     28,       244,        1844,         13260, ...;
   4,    244,      5856,      101620,       1511160, ...;
   8,   1844,    101620,     3455080,      91981880, ...;
  16,  13260,   1511160,    91981880,    4047202720, ...;
  32,  93684,  20663388,  2121603436,  146321752612, ...;
  64, 657836, 269011408, 44675623468, 4648698508440, ...;
Triangle T(n,k) begins as:
    1;
    2,      2;
    4,     28,        4;
    8,    244,      244,        8;
   16,   1844,     5856,     1844,       16;
   32,  13260,   101620,   101620,    13260,       32;
   64,  93684,  1511160,  3455080,  1511160,    93684,     64;
  128, 657836, 20663388, 91981880, 91981880, 20663388, 657836, 128;
		

Crossrefs

Cf. A000079, A008546 (row sums), A142460, A257623.
Similar sequences listed in A256890.

Programs

  • Mathematica
    t[n_, k_, p_, q_]:= t[n, k, p, q] = If[n<0 || k<0, 0, If[n==0 && k==0, 1, (p*k+q)*t[n-1,k,p,q] + (p*n+q)*t[n,k-1,p,q]]];
    T[n_, k_, p_, q_]= t[n-k, k, p, q];
    Table[T[n,k,5,2], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Mar 01 2022 *)
  • Sage
    @CachedFunction
    def t(n,k,p,q):
        if (n<0 or k<0): return 0
        elif (n==0 and k==0): return 1
        else: return (p*k+q)*t(n-1,k,p,q) + (p*n+q)*t(n,k-1,p,q)
    def A257614(n,k): return t(n-k,k,5,2)
    flatten([[A257614(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Mar 01 2022

Formula

T(n, k) = t(n-k, k), where t(0,0) = 1, t(n,m) = 0 if n < 0 or m < 0, else t(n,m) = f(m)*t(n-1,m) + f(n)*t(n,m-1), and f(n) = 5*n + 2.
Sum_{k=0..n} T(n, k) = A008546(n).
From G. C. Greubel, Mar 01 2022: (Start)
t(k, n) = t(n, k).
T(n, n-k) = T(n, k).
t(0, n) = T(n, 0) = A000079(n). (End)