A108655 Primes that are sums of the squares of two semiprimes.

97, 181, 241, 277, 421, 457, 541, 641, 661, 709, 757, 821, 1109, 1117, 1237, 1301, 1381, 1597, 1621, 1669, 1709, 1901, 2069, 2341, 2381, 2417, 2437, 2557, 2617, 2677, 2741, 2797, 3041, 3061, 3221, 3557, 3637, 3701, 3733, 3989, 4241, 4261, 4421, 4517

Offset: 1

Author

Reinhard Zumkeller, Jul 07 2005

Keywords

• nonn

Comments

Subsequence of A002144.

a(n) = A074985(i) + A074985(j) for appropriate i and j.

Examples

			A000040(733) = 5557 = 81 + 5476 = (3*3)^2 + (2*37)^2 =
A001358(3)^2 + A001358(25)^2 = A074985(3) + A074985(25),
therefore 5557 is a term.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000404, A001358, A000290.

Programs

Haskell

a108655 n = a108655_list !! (n-1)
a108655_list = filter f a000040_list where
   f p = any (> 0) $ map (a064911 . a037213 . (p -)) $
                         takeWhile (< p) a074985_list
-- Reinhard Zumkeller, Aug 09 2012