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Search: id:A122460
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| A122460 |
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Triangular array of averages of two odd primes. |
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+0
1
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| 4, 7, 6, 10, 9, 9, 13, 12, 12, 12, 17, 17, 15, 15, 15, 22, 21, 19, 20, 18, 18, 25, 24, 24, 24, 22, 23, 21, 31, 29, 27, 27, 27, 27, 25, 26, 35, 33, 33, 32, 30, 30, 30, 30, 30, 38, 38, 37, 36, 36, 35, 33, 33, 35, 34, 43, 42, 40, 41, 40, 39, 39, 38, 38, 37, 39, 50, 47, 45, 45, 43
(list; table; graph; listen)
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OFFSET
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1,1
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FORMULA
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T(n,k) = (1/2)*(p(k)+p(2n+1-k)) for k=1,2,...,n, where p(1)=3, p(2)=5, ... are the odd primes.
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EXAMPLE
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First six rows:
4
7 6
10 9 9
13 12 12 12
17 17 15 15 15
22 21 19 20 18 18
Row 3 is formed from the first 6 odd primes:
3 5 7 11 13 17 --> (3+17)/2 (5+13)/2 (7+11)/2
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CROSSREFS
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Cf. A122459.
Adjacent sequences: A122457 A122458 A122459 this_sequence A122461 A122462 A122463
Sequence in context: A140877 A069286 A079354 this_sequence A063845 A019714 A021681
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KEYWORD
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nonn,tabl
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu), Sep 08 2006
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