OFFSET
1,2
REFERENCES
R. K. Guy, "s-Additive sequences," preprint, 1994.
LINKS
S. R. Finch, Are 0-additive sequences always regular?, Amer. Math. Monthly, 99 (1992), 671-673.
EXAMPLE
a(5) cannot be 5=2+3. It cannot be 6=2+4. It cannot be 7=3+4, and becomes a(5)=8.
a(6) cannot be 9=2+3+4. It cannot be 10=2+8. It cannot be 11=3+8. It cannot be 12 = 4+8. It cannot be 13=2+3+8. It cannot be 14=2+4+8. It cannot be 15=3+4+8, and becomes a(6)=16.
MAPLE
A244750:= proc(n)
option remember;
if n <= 4 then
op(n, [0, 2, 3, 4]);
else
prev := {seq(procname(k), k=1..n-1)} ;
for a from procname(n-1)+1 do
awrks := true ;
for asub in combinat[choose](prev) do
if add(p, p=asub) = a then
awrks := false;
break;
end if;
end do:
if awrks then
return a;
end if;
end do:
end if;
end proc:
for n from 1 do
print(A244750(n)) ;
end do: # R. J. Mathar, Jul 12 2014
MATHEMATICA
f[s_List] := f[n] = Block[{k = s[[-1]] + 1, ss = Union[Plus @@@ Subsets[s]]}, While[ MemberQ[ss, k], k++]; Append[s, k]]; Nest[ f[#] &, {0, 2, 3, 4}, 16]
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane and Robert G. Wilson v, Jul 05 2014
EXTENSIONS
Corrected by R. J. Mathar, Jul 12 2014
STATUS
approved