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 A078136 Numbers having exactly one representation as sum of squares>1. 8
 4, 8, 9, 12, 13, 17, 18, 21, 22, 26, 27, 30, 31, 35, 39 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A078134(a(n))=1. The sequence is finite with a(15)=39 as last term, since numbers m>39 can be represented as sums of squares>1 (even of squares of primes and even of squares of 2, 3 and 4 and even of squares of 2, 3 and 5) in at least two ways. Proof: if m=40+4k, k>=0, then m=(k+10)*2^2=(k+1)*2^2+4*3^2; if m=41+4k, then m=(k+8)*2^2+3^2=(k+4)*2^2+5^2; if m=42+4k, then m=(k+6)*2^2+2*3^2=(k+2)*2^2+3^2+5^2; if m=43+4k, then m=(k+4)*2^2+3*3^2=k*2^2+2*3^2+5^2. - Hieronymus Fischer, Nov 11 2007 LINKS Eric Weisstein's World of Mathematics, Square Number. CROSSREFS Cf. A000290, A078137, A078135, A078130. Cf. A078134, A078139, A090677, A078137, A134754, A134755. Sequence in context: A078137 A294574 A010453 * A291791 A037973 A044844 Adjacent sequences:  A078133 A078134 A078135 * A078137 A078138 A078139 KEYWORD nonn,fini,full AUTHOR Reinhard Zumkeller, Nov 19 2002 STATUS approved

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Last modified August 18 07:09 EDT 2019. Contains 326072 sequences. (Running on oeis4.)