OFFSET
0,2
LINKS
Ivan Neretin, Table of n, a(n) for n = 0..10000
FORMULA
MATHEMATICA
Accumulate[Flatten[Table[{PadRight[{}, 3*2^n, 1], PadRight[{}, 3*2^n, 2]}, {n, 0, 4}]]] (* Harvey P. Dale, May 04 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 23 2003
STATUS
approved