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Search: id:A146985
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| A146985 |
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I call this sequence "symmetrical spooky primes" as two prime combinations are used in cryptography: f(n)=If[n==0,1,Prime[n]]; t(n,m)=f(n-m)*f(n). |
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+0
1
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| 1, 2, 2, 3, 4, 3, 5, 6, 6, 5, 7, 10, 9, 10, 7, 11, 14, 15, 15, 14, 11, 13, 22, 21, 25, 21, 22, 13, 17, 26, 33, 35, 35, 33, 26, 17, 19, 34, 39, 55, 49, 55, 39, 34, 19, 23, 38, 51, 65, 77, 77, 65, 51, 38, 23, 29, 46, 57, 85, 91, 121, 91, 85, 57, 46, 29
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums are:{1, 4, 10, 22, 43, 80, 137, 222, 343, 508, 737}. The sequence to Floor[n/2] is a way to get all the combinations of primes with one less than the other.
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FORMULA
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f(n)=If[n==0,1,Prime[n]]; t(n,m)=f(n-m)*f(n).
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EXAMPLE
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{1}, {2, 2}, {3, 4, 3}, {5, 6, 6, 5}, {7, 10, 9, 10, 7}, {11, 14, 15, 15, 14, 11}, {13, 22, 21, 25, 21, 22, 13}, {17, 26, 33, 35, 35, 33, 26, 17}, {19, 34, 39, 55, 49, 55, 39, 34, 19}, {23, 38, 51, 65, 77, 77, 65, 51, 38, 23}, {29, 46, 57, 85, 91, 121, 91, 85, 57, 46, 29}
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MATHEMATICA
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Clear[f, t, n, m]; f[n_] := If[n == 0, 1, Prime[n]]; t[n_, m_] = f[n - m]*f[m]; Table[t[n, m], {n, 0, 10}, {m, 0, n}]; Flatten[%]
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CROSSREFS
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Sequence in context: A026350 A165634 A128282 this_sequence A132993 A106408 A143061
Adjacent sequences: A146982 A146983 A146984 this_sequence A146986 A146987 A146988
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KEYWORD
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easy,nonn
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Nov 04 2008
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