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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
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OFFSET
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1,3
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COMMENTS
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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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LINKS
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EXAMPLE
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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
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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