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A063395
T(2n,n) with T(n,m) as in A063394.
1
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
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
KEYWORD
nonn
AUTHOR
Floor van Lamoen, Jul 16 2001
EXTENSIONS
More terms from Ralf Stephan, Mar 23 2004
STATUS
approved