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Least positive integer multiples of angle x such that their direction cosines form a unit vector: sum(k>0, cos(a(k)*x)^2)=1, where a(1)=1, a(n+1)>a(n) and x=(5/4).
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%I #5 Mar 30 2012 18:36:33

%S 1,2,4,6,14,34,44,49,137,142,235,333,426,519,710,994,1278,1562,1846,

%T 2130,2414,2698,2982,3266,3550,3834,4118,4402,4686,4970,5254,5538,

%U 5822,6106,6390,6674,6958,7242,7526,7810,8094,8378,8662,8946,9230,9514,9798

%N Least positive integer multiples of angle x such that their direction cosines form a unit vector: sum(k>0, cos(a(k)*x)^2)=1, where a(1)=1, a(n+1)>a(n) and x=(5/4).

%o (PARI) x=(5/4); z=cos(x)^2; a=1; for(n=1,64,b=a+1; while(z+cos(b*x)^2>1,b++); z=z+cos(b*x)^2; a=b; print1(b,","))

%Y Cf. A080136, A080137, A080138, A080139, A080140.

%K nonn

%O 1,2

%A _Paul D. Hanna_, Feb 04 2003