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A266603
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Irregular triangle T(n,k) read by rows: numbers such that 2^n +/- T(n,k) are both primes.
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0
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0, 1, 3, 5, 3, 13, 9, 15, 21, 29, 3, 33, 45, 21, 39, 45, 69, 99, 105, 111, 15, 27, 57, 75, 93, 117, 153, 177, 183, 243, 253, 9, 45, 81, 129, 165, 231, 249, 261, 285, 315, 345, 375, 399, 441, 459, 465, 471, 501
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OFFSET
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1,3
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COMMENTS
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Except when k is maximum for a given n, all elements must be odd multiples of 3. Specifically: T(n,k) == {9,15,21} mod 30 when n is odd and T(n,k) == {3,15,27} mod 30 when n is even. The only exception is T(3,1)=3.
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LINKS
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Table of n, a(n) for n=1..49.
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EXAMPLE
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Triangle starting with T(1,1):
0
1
3 5
3 13
9 15 21 29
3 33 45
21 39 45 69 99 105 111
15 27 57 75 93 117 153 177 183 243 253
9 45 81 129 165 231 249 261 285 315 345 375 399 441 459 465 471 501
...
T(5,4)=29 because 2^5=32; 32+29=61 and 32-29=3 are prime.
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CROSSREFS
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Cf. A000040 (prime numbers).
Sequence in context: A089948 A336806 A023583 * A121278 A023587 A172003
Adjacent sequences: A266600 A266601 A266602 * A266604 A266605 A266606
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KEYWORD
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nonn,tabf
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AUTHOR
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Bob Selcoe, Feb 21 2016
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STATUS
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approved
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