A063395 T(2n,n) with T(n,m) as in A063394.

1, 3, 19, 131, 979, 7683, 62099, 511619, 4271699, 36018179, 305998099, 2615234691, 22459983059, 193665818115, 1675580699539, 14538892408451, 126467748738899, 1102484411211779, 9629327766561299, 84247346901823619, 738200425192338899, 6477139329614712323

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Formula

G.f.: 4x/sqrt(1-10x+9x^2) + (1-2x)/(1-x). - Ralf Stephan, Mar 23 2004

Conjecture: (-n+1)*a(n) +(11*n-17)*a(n-1) +(-19*n+43)*a(n-2) +9*(n-3)*a(n-3)=0. - R. J. Mathar, Jun 10 2013

Prog

(PARI) m=matrix(50, 50):for(i=1, 50, m[1, i]=1:m[i, 1]=1):for(i=2, 50, for(k=1, i, x=i-k+1: if(m[x, k]==0, m[x, k]=sum(n=2, k-1, m[x, n])+sum(n=2, x-1, m[n, k])+k+x-1))):for(n=1, 24, print1(m[n, n]", ")) /* Ralf Stephan */

Crossrefs

Equals 4*A084771(n-1) - 1, n>0.

Sequence in context: A219053 A074713 A199484 * A226459 A256092 A370159

Adjacent sequences: A063392 A063393 A063394 * A063396 A063397 A063398

Keyword

nonn

Author

Floor van Lamoen, Jul 16 2001

Extensions

More terms from Ralf Stephan, Mar 23 2004

Status

approved