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%I #8 Feb 03 2017 18:45:12
%S 1,1,1,2,2,2,3,4,3,3,5,4,4,5,7,5,5,9,6,6,8,9,7,7,13,8,8,12,11,9,10,15,
%T 10,10,16,13,11,14,17,12,12,20,14,13,18,19,14,15,24,15,15,22,20,16,19,
%U 26,17,17,27,20,18,23,27,19,19,33,20,20,28,27,21,23
%N Number of sets of exactly n positive integers <= n+2 having a square element sum.
%H Alois P. Heinz, <a href="/A281965/b281965.txt">Table of n, a(n) for n = 0..1000</a>
%F a(n) = A281871(n+2,n).
%e a(7) = 4: {1,2,3,6,7,8,9}, {1,2,4,5,7,8,9}, {1,3,4,5,6,8,9}, {2,3,4,5,6,7,9}.
%e a(8) = 3: {1,2,3,4,5,6,7,8}, {1,3,5,6,7,8,9,10}, {2,3,4,6,7,8,9,10}.
%e a(9) = 3: {1,2,3,4,5,6,7,10,11}, {1,2,3,4,5,6,8,9,11}, {1,2,3,4,5,7,8,9,10}.
%Y A diagonal of A281871.
%K nonn,look
%O 0,4
%A _Alois P. Heinz_, Feb 03 2017
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