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 A130808 Magic side-sum constants of magic triangles of Yates using the numbers 1 to 9. 1
 17, 19, 20, 21, 23 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A magic triangle of Yates, with nine numbers a,b,c,d,e,f,g,h,i has the form a d f e g b h i c The corner sum C = a+b+c and magic side-sum S = a+d+e+b = b+h+i+c = a+f+g+c are related by C=3*(S - 15). Since here, 1+2+3 <= C <= 7+8+9, we have 17 <= S <= 23. Finally, an argument based on a contradiction proof eliminates the values of 18 and 22 for S. REFERENCES U. Nagamani, "The magic triangles of Yates" in 'Science Reporter', pp. 65-66, Jan. 1978, Vol. 15, No. 1, CSIR, New Delhi. LINKS EXAMPLE All the magic triangles are illustrated: 1 1 4 3 7 9 6 8 9 8 1 8 7 3 6 5 7 6 2 3 9 4 2 5 1 2 8 4 3 4 5 3 7 5 7 2 6 6 5 1 9 8 2 4 9 CROSSREFS Sequence in context: A041610 A042399 A156656 * A194389 A030127 A115849 Adjacent sequences: A130805 A130806 A130807 * A130809 A130810 A130811 KEYWORD fini,full,nonn AUTHOR Lekraj Beedassy, Aug 20 2007 STATUS approved

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Last modified December 3 05:56 EST 2022. Contains 358512 sequences. (Running on oeis4.)