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%I #5 Sep 05 2023 20:16:57
%S 12,13,14,15,16,17,18,23,24,57,25,26,27,28,34,35,36,37,38,45,46,58,67,
%T 68,47,78
%N Letters of the English alphabet represented by flag semaphores encoding the positions z of the 2 flags by a two-digit decimal number z = 10*x + y, 1 <= x < y <= 8.
%C Flag positions {x, y}:
%C . . . . . . . . . \ . . . | . . . / . . . . . .
%C . O . . O . - O . . O . . O . . O . . O - . O .
%C . | . / . . . . . . . . . . . . . . . . . . . \
%C 1 2 3 4 5 6 7 8
%C i.e., angle phi(x) = (7 - x)*Pi/4.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Flag_semaphore">Flag semaphore</a>
%e . . . . . . \ . . . | . . . / . . . . . .
%e . O . - O . . O . . O . . O . . O - . O .
%e / | . . | . . | . . | . . | . . | . . | \
%e A 12 B 13 C 14 D 15 E 16 F 17 G 18
%e .
%e . . . \ . . . | . . | . . . / . . . . . .
%e - O . . O . . O - . O . . O . . O - . O .
%e / . . / . . . . . / . . / . . / . . / . \
%e H 23 I 24 J 57 K 25 L 26 M 27 N 28
%e .
%e \ . . . | . . . / . . . . . . \ | . \ . /
%e - O . - O . - O . - O - - O . . O . . O .
%e . . . . . . . . . . . . . . \ . . . . . .
%e O 34 P 35 Q 36 R 37 S 38 T 45 U 46
%e .
%e . | . . . / . . / \ . . . . . . | / \ . .
%e . O . . O - . O . . O - . O - . O . . O .
%e . . \ . . . . . \ . . . . . \ . . . . . \
%e V 58 W 67 X 68 Y 47 Z 78 (# 56 - 48)
%K nonn,base,fini,full
%O 1,1
%A _Hugo Pfoertner_, Sep 05 2023