OFFSET
1,1
COMMENTS
Numbers k such that (-1)^k*A008347(k) is a perfect square. - R. J. Mathar, Feb 21 2010
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..300
EXAMPLE
2 - 3 + 5 = 4, thus a(1)=3;
2 - 3 + 5 - 7 + 11 - 13 + 17 - 19 + 23 = 16, thus a(2)=9.
MATHEMATICA
Flatten[Position[Accumulate[Times@@@Partition[Riffle[Prime[Range[ 20000]], {1, -1}, {2, -1, 2}], 2]], _?(IntegerQ[Sqrt[#]]&)]] (* Harvey P. Dale, Mar 19 2013 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Ctibor O. Zizka, Feb 14 2010
EXTENSIONS
Six more terms from R. J. Mathar, Feb 21 2010
STATUS
approved