OFFSET
1,2
MATHEMATICA
a={1, 4}; Do[If[MemberQ[a, n], b=a[[n-2]]+3, b=a[[n-2]]+1]; AppendTo[a, b], {n, 3, 70}]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Mar 11 2007
STATUS
approved