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A122506
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A symmetrical triangular array based on A018805 constructed by hand by adding ones between the primes and making the result symmetrical.
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0
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1, 1, 3, 1, 1, 3, 1, 7, 1, 3, 1, 1, 3, 1, 7, 1, 11, 1, 7, 1, 3, 1, 1, 3, 1, 7, 1, 11, 1, 19, 1, 11, 1, 7, 1, 3, 1, 1, 3, 1, 7, 1, 11, 1, 19, 1, 23, 1, 19, 1, 11, 1, 7, 1, 3, 1
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| The first two terms past one come from removing the zeros from coefficients here: Expand[(x^2 - x - 1)*(x^2 + x - 1)] Abs[CoefficientList[1 - 3 x^2 + x^4, x]] {1, 0, 3, 0, 1} Expand[(x^3 - 2*x^2 - x + 1)*(x^3 - x^2 - 2*x + 1)] Abs[CoefficientList[1 - 3 x - x^2 + 7 x^3 - x^4 - 3 x^5 + x^6, x]] {1, 3, 1, 7, 1, 3, 1}
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FORMULA
| none available at this time
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EXAMPLE
| 1
1, 3, 1
1, 3, 1, 7, 1, 3, 1
1, 3, 1, 7, 1, 11, 1, 7, 1, 3, 1
1, 3, 1, 7, 1, 11, 1, 19, 1, 11, 1, 7, 1, 3, 1
1, 3, 1, 7, 1, 11, 1, 19, 1, 23, 1, 19, 1, 11, 1, 7, 1, 3, 1
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MATHEMATICA
| a0 = {{1}, {1, 3, 1}, {1, 3, 1, 7, 1, 3, 1}, {1, 3, 1, 7, 1, 11, 1, 7, 1, 3, 1}, {1, 3, 1, 7, 1, 11, 1, 19, 1, 11, 1, 7, 1, 3, 1}, {1, 3, 1, 7, 1, 11, 1, 19, 1, 23, 1, 19, 1, 11, 1, 7, 1, 3, 1}} Flatten[a0]
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CROSSREFS
| Cf. A018805.
Sequence in context: A131781 A082465 A131327 * A010274 A137728 A054398
Adjacent sequences: A122503 A122504 A122505 * A122507 A122508 A122509
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KEYWORD
| nonn,uned,tabl
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AUTHOR
| Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 15 2006
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