OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1601 (rows 1..40)
D. H. Lehmer, Generalized Eulerian numbers, J. Combin. Theory Ser.A 32 (1982), no. 2, 195-215. MR0654621 (83k:10026).
FORMULA
From Andrew Howroyd, May 18 2020: (Start)
T(n,k) = k*T(n-1,k) - (n-k)*T(n-1,k-1) - (2*n-k)*T(n-1,k-2) for n > 1.
A047681(n) = Sum_{k>=1} T(2*n, k).
(End)
EXAMPLE
Triangle begins
1, 2;
1, 4, 1;
1, 7, 0, -7, -1;
1, 12, -12, -56, -12, 12, 1;
1, 21, -67, -284, 0, 284, 67, -21, -1;
1, 38, -273, -1170, 753, 3408, 753, -1170, -273, 38, 1;
...
PROG
(PARI)
T(n, r=2)={my(R=vector(n)); R[1]=[1..r]; for(n=2, n, my(u=R[n-1]); R[n]=vector(r*n-1, k, sum(j=0, r, (k - j*n)*if(k>j && k-j<=#u, u[k-j], 0)))); R}
{ my(A=T(7)); for(n=1, #A, print(A[n])) } \\ Andrew Howroyd, May 18 2020
CROSSREFS
KEYWORD
sign,tabf
AUTHOR
N. J. A. Sloane, Apr 05 2012
EXTENSIONS
Terms a(38) and beyond from Andrew Howroyd, May 18 2020
STATUS
approved