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A065305
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Triangular array giving means of two odd primes: T(n,k) = (n-th prime + k-th prime)/2, n >= k >= 2.
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8
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3, 4, 5, 5, 6, 7, 7, 8, 9, 11, 8, 9, 10, 12, 13, 10, 11, 12, 14, 15, 17, 11, 12, 13, 15, 16, 18, 19, 13, 14, 15, 17, 18, 20, 21, 23, 16, 17, 18, 20, 21, 23, 24, 26, 29, 17, 18, 19, 21, 22, 24, 25, 27, 30, 31, 20, 21, 22, 24, 25, 27, 28, 30, 33, 34, 37, 22, 23, 24, 26, 27, 29, 30
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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2,1
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LINKS
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EXAMPLE
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3; 4,5; 5,6,7; 7,8,9,11; ...
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MAPLE
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seq(seq((ithprime(i)+ithprime(j))/2, j=2..i), i=2..20)
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PROG
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(Haskell)
import Data.List (inits)
a065305 n k = a065305_tabl !! (n-2) !! (k - 1)
a065305_row n = a065305_tabl !! (n-2)
a065305_tabl = zipWith (map . (flip div 2 .) . (+))
a065091_list $ tail $ inits a065091_list
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CROSSREFS
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a(n, k) = A065342(n, k)/2 [but note different offsets]
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KEYWORD
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AUTHOR
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Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Oct 29 2001
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STATUS
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approved
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