A141755 Product of two primes whose sum is a perfect square.

4, 14, 39, 46, 55, 94, 155, 158, 183, 203, 291, 295, 299, 323, 334, 446, 579, 583, 695, 718, 799, 878, 943, 955, 959, 979, 1191, 1255, 1411, 1454, 1678, 1703, 2019, 2059, 2159, 2174, 2219, 2395, 2419, 2446, 2491, 2734, 2855, 3043, 3063, 3443, 3459, 3503, 3694

Offset

1,1

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Mathematica

Take[ Sort[ Times @@@ Select[ Subsets[ Array[ Prime, 290], {2}], IntegerQ[ Sqrt[ #[[2]] + #[[1]]]] &]], 48]
nn=4000; fQ[n_] := Module[{p, e}, If[n < 2, False, {p, e} = Transpose[FactorInteger[n]]; If[Total[e] != 2, False, IntegerQ[Sqrt[Total[p*e]]]]]]; Select[Range[nn], fQ] (* T. D. Noe, Mar 22 2012 *)

Prog

(Haskell)
a141755 n = a141755_list !! (n-1)
a141755_list = filter f a001358_list where
   f x = a010052' (spf + x `div` spf) == 1 where spf = a020639 x
-- Reinhard Zumkeller, Apr 06 2015

Crossrefs

Cf. A000040, A000290, A143416.

Cf. A001358, A020639, A010052.

Sequence in context: A124615 A317606 A114845 * A064463 A130423 A266423

Adjacent sequences: A141752 A141753 A141754 * A141756 A141757 A141758

Keyword

nonn

Author

David Spector (spectord(AT)ccsu.edu) and Robert G. Wilson v, Aug 31 2008

Status

approved