%I M0542
%S 1,2,3,4,6,7,8,9,11,12,14,16,18,19,21,22,23,24,27,28,31,32,33,36,38,
%T 42,43,44,46,47,48,49,54,56,57,59,62,63,64,66,67,69,71,72,76,77,79,81,
%U 83,84,86,88,92,93,94,96,98,99,103,107,108,112,114,118,121,124,126,127
%N Nonhypotenuse numbers (squares that are not the sums of 2 distinct nonzero squares).
%C Also numbers with no prime factors of form 4*k+1.
%C m is a term iff A072438(m) = m.
%C Density 0.  _Charles R Greathouse IV_, Apr 16 2012
%C A005089(a(n)) = 0.  _Reinhard Zumkeller_, Jan 07 2013
%C Closed under multiplication. Primitive elements are 2 and the primes of form 4*k+3.  _JeanChristophe HervĂ©_, Nov 17 2013
%D S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 98104.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H T. D. Noe, <a href="/A004144/b004144.txt">Table of n, a(n) for n = 1..1000</a>
%H S. R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/constant/lr/lr.html">LandauRamanujan Constant</a>
%H D. Shanks, <a href="http://www.fq.math.ca/Scanned/134/shanks.pdf">Nonhypotenuse numbers</a>, Fib. Quart., 13:4 (1975), pp. 319321.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PythagoreanTriple.html">Pythagorean Triple</a>
%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%t fQ[n_] := If[n > 1, First@ Union@ Mod[ First@# & /@ FactorInteger@ n, 4] != 1, True]; Select[ Range@ 127, fQ]
%o (PARI) is(n)=n==1vecmin(factor(n)[,1]%4)>1 \\ _Charles R Greathouse IV_, Apr 16 2012
%o (Haskell)
%o import Data.List (elemIndices)
%o a004144 n = a004144_list !! (n1)
%o a004144_list = map (+ 1) $ elemIndices 0 a005089_list
%o  _Reinhard Zumkeller_, Jan 07 2013
%Y Complement of A009003.
%Y Cf. A072437.
%K nonn
%O 1,2
%A _N. J. A. Sloane_.
%E More terms from _Reinhard Zumkeller_, Jun 17 2002
