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%I #5 Mar 12 2014 16:36:57
%S 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,
%T 1,7,1,3,1,1,3,1,7,1,11,1,19,1,23,1,19,1,11,1,7,1,3,1
%N A symmetrical triangular array based on A018805 constructed by hand by adding ones between the primes and making the result symmetrical.
%C 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}
%F none available at this time
%e 1
%e 1, 3, 1
%e 1, 3, 1, 7, 1, 3, 1
%e 1, 3, 1, 7, 1, 11, 1, 7, 1, 3, 1
%e 1, 3, 1, 7, 1, 11, 1, 19, 1, 11, 1, 7, 1, 3, 1
%e 1, 3, 1, 7, 1, 11, 1, 19, 1, 23, 1, 19, 1, 11, 1, 7, 1, 3, 1
%t 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]
%Y Cf. A018805.
%K nonn,uned,tabl
%O 1,3
%A _Roger L. Bagula_, Sep 15 2006
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