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A154722
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Triangle read by rows in which row n lists: n, in the center of the row and the pairs of non-composite numbers that are equidistant to n, as shown below in the example.
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13
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1, 1, 2, 3, 1, 3, 5, 1, 3, 4, 5, 7, 3, 5, 7, 1, 5, 6, 7, 11, 1, 3, 7, 11, 13, 3, 5, 8, 11, 13, 1, 5, 7, 9, 11, 13, 17, 1, 3, 7, 10, 13, 17, 19, 3, 5, 11, 17, 19, 1, 5, 7, 11, 12, 13, 17, 19, 23, 3, 7, 13, 19, 23, 5, 11, 14, 17, 23, 1, 7, 11, 13, 15
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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LINKS
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Nathaniel Johnston, Table of n, a(n) for n = 1..5000
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EXAMPLE
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Triangle begins:
. . . . . . . . . . . . . . .1
. . . . . . . . . . . . . 1, 2, 3
. . . . . . . . . . . .1, .. 3, .. 5
. . . . . . . . . . 1, .. 3, 4, 5, .. 7
. . . . . . . . ... .. 3, .. 5, .. 7, .. .
. . . . . . . 1, .. .. .. 5, 6, 7, .. .. .,11
. . . . . .1, .. 3, .. .. .. 7, .. .. ..11, ..13
. . . . .. .. 3, .. 5, .. .. 8, .. ..11, ..13, .. .
. . .1, .. .. .. 5, .. 7, .. 9, ..11, ..13, .. .. ..17
. 1, .. 3, .. .. .. 7, .. .,10, .. ..13, .. .. ..17, ..19
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MAPLE
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isnotcomp:=proc(n)return (n=1 or isprime(n)) end:
for n from 1 to 10 do for k from 1 to 2*n-1 do if(k=n or (isnotcomp(k) and isnotcomp(2*n-k)))then print(k):fi:od:od: # Nathaniel Johnston, Apr 18 2011
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CROSSREFS
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Cf. A000040, A008578, A154720, A154721, A154723, A154724, A154725, A154726, A154727.
Sequence in context: A185311 A214582 A050375 * A194760 A035517 A099471
Adjacent sequences: A154719 A154720 A154721 * A154723 A154724 A154725
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KEYWORD
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easy,nonn,tabf
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AUTHOR
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Omar E. Pol, Jan 14 2009
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EXTENSIONS
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a(45) - a(73) from Nathaniel Johnston, Apr 18 2011
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STATUS
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approved
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