OFFSET
1,1
COMMENTS
a(n) = n for n > 4.
Except for the integers 1 & 4 which are interchanged, the sequence is in order. Proof: Except for the first three triangular numbers (A000217), {0, 1, 3}, they are all composite. - Robert G. Wilson v, Jun 27 2010
LINKS
FORMULA
G.f.: 3 - 3*x^3 + 1/(x-1)^2. - Sergei N. Gladkovskii, Oct 16 2012
EXAMPLE
Partial sums are 4,6,9,10,15,21,...
MATHEMATICA
f[s_List] := Block[{k = 0, t = Plus @@ s}, While[MemberQ[s, k] || PrimeQ[t + k] || t + k < 2, k++ ]; Append[s, k]]; Rest@ Nest[f, {0}, 72] (* Robert G. Wilson v, Jun 27 2010 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Jun 23 2010
EXTENSIONS
a(40)-a(72) from Robert G. Wilson v, Jun 27 2010
STATUS
approved