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A161190
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Sums of prime points found in four grids in each corner of a square.
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5
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281, 414, 857, 942, 1124, 2569, 1295, 1433, 1094, 2426, 2730, 3000, 2459, 2575, 1818, 4991, 5331, 3363, 1163, 5006, 5226, 1381, 7213, 7493, 4729, 8217, 3456, 3546, 3684, 5615, 7834, 8090, 6243, 2143, 8862, 11407, 9396, 12019, 4906, 7631, 2591, 13411
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OFFSET
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1,1
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COMMENTS
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When the points are marked on drawn lines the concavity is apparent.
The lines are indicated with capital letters A through G (see Fig. 6 in Link)
- A
B 1 7 12 16 19 21
C 2 8 13 17 20
D 3 9 14 18
E 4 10 15
F 5 11
G 6
Reading diagonally across the bottom of the first of 4 diagonals:
6,11,15,18,20,21. The next 3 diagonals are formed by adding 1 to 21, e.g.,
22,27,31,34,36,37
38,43,47,50,52,53
54,59,63,66,68,69. This grid is numbered 1, and the next, 2, starts at 70.
Each numbered set of 4 grids fills the corners of a square delineating and surrounding a circle suggested by the 24 numbers above on its circumference.
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LINKS
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EXAMPLE
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a(1)=281 because that is the sum of the prime points in the first set of 4 lower diagonals in the first 4 corner grids: (11+31+37+43+47+53+59=281).
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PROG
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(UBASIC)
20 F=5
30 A=F+1:print A; :if A=prmdiv(A) then S=S+B:print "*";
40 B=A+5:print B; :if B=prmdiv(B) then S=S+B:print "*";
50 C=B+4:print C; :if C=prmdiv(C) then S=S+C:print "*";
60 D=C+3:print D; :if D=prmdiv(D) then S=S+D:print "*";
70 E=D+2:print E; :if E=prmdiv(E) then S=S+E:print "*";
80 F=E+1:print F; :if F=prmdiv(F) then S=S+F:print "*";
90 R=R+1:if R=4 and S=prmdiv(S) then print S; "*";
100 if R=4 then print R; S; :T=T+1:print T:R=0:S=0
110 stop:goto 30
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CROSSREFS
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KEYWORD
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easy,nonn,uned
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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