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A108655
Primes that are sums of the squares of two semiprimes.
1
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
1,1
COMMENTS
Subsequence of A002144.
a(n) = A074985(i) + A074985(j) for appropriate i and j.
LINKS
EXAMPLE
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.
PROG
(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
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 07 2005
STATUS
approved