12,1

B. Malesevic: Some combinatorial aspects of differential operation composition on the space R^n, Univ. Beograd, Publ. Elektrotehn. Fak., Ser. Mat. 9 (1998), 29-33.

B. Malesevic, Some combinatorial aspects of differential operation composition on the space R^n

f(k+6)=6*f(k+4)-10*f(k+2)+4*f(k)

NUM := proc(k :: integer) local i, j, n, Fun, Identity, v, A; n:=12; # <- DIMENSION Fun:=(i, j)->piecewise(((j=i+1) or (i+j=n+1)), 1, 0); Identity:=(i, j)->piecewise(i=j, 1, 0); v:=matrix(1, n, 1); A:=piecewise(k>1, (matrix(n, n, Fun))^(k-1), k=1, matrix(n, n, Identity)); return(evalm(v&*A&*transpose(v))[1, 1]); end:

Cf. A090989-A090995.

Sequence in context: A098955 A124885 A115745 this_sequence A115709 A115703 A014633

Adjacent sequences: A129636 A129637 A129638 this_sequence A129640 A129641 A129642

nonn

Branko Malesevic (malesevic(AT)etf.bg.ac.yu), May 31 2007