OFFSET
1,3
EXAMPLE
Triangle begins:
1;
1,3,1;
1,3,1,11,1,3,1;
...
MATHEMATICA
S[0] = {{1}}; S[n_] := S[n] = ArrayFlatten[{{S[n-1], S[n-1] + S[n-1][[-1, -1]]}, {S[n-1] + 2 S[n-1][[-1, -1]], S[n-1] + 3 S[n-1][[-1, -1]]}}];
row[n_] := S[n][[1]] // Differences;
Array[row, 6] // Flatten
(* Second program (without matrices): *)
ro[0] = {1}; ro[n_] := Join[ro[n-1], {(2^(2n+1)+1)/3}, ro[n-1]];
Array[ro, 6, 0] // Flatten (* Jean-François Alcover, Sep 05 2017 *)
CROSSREFS
KEYWORD
nonn,tabf,easy,nice
AUTHOR
Tidjani Negadi (t-negadi(AT)usa.net), May 21 2000
EXTENSIONS
More terms from Naohiro Nomoto, Sep 12 2001
STATUS
approved