OFFSET
1,1
COMMENTS
The sequence contains every square greater than 1.
Conjecture: the sequence contains infinitely many primes.
FORMULA
{k: A307597(k) > 0 }. - R. J. Mathar, Apr 28 2020
EXAMPLE
24 = 3 + 21, so 24 is in the sequence.
MATHEMATICA
r = 120; lst = Table[0, {r}]; lim = Floor[Sqrt[8*r - 7]]; Do[num = (i^2 + i)/2 + (j^2 + j)/2; If[num <= r, lst[[num]]++], {i, lim}, {j, i - 1}]; Flatten@Position[lst, n_ /; n > 0]
With[{nn=20}, Select[Union[Total/@Subsets[Accumulate[Range[nn]], {2}]], #<= (nn(nn+1))/2+1&]] (* Harvey P. Dale, Jul 26 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Arkadiusz Wesolowski, Dec 02 2015
STATUS
approved