OFFSET
1,3
COMMENTS
The records of a(n) are a(1)=1, a(3)=2, a(12)=3, a(132)=4,... Is the sequence unbounded?
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
FORMULA
MATHEMATICA
nn = 2000; ps = Prime[Range[PrimePi[Sqrt[nn]]]]; t = Flatten[Table[ ps[[i]]^2 + ps[[j]]^2, {i, Length[ps]}, {j, i, Length[ps]}]]; t =
Select[t, # <= nn &]; PrimeNu[Sort[Transpose[Select[Tally[t], #[[2]] == 1 &]][[1]]]] (* G. C. Greubel, May 16 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Aug 03 2012
STATUS
approved