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Expansions of p(x,n)=(x^n - 1)*(x^(n + 1) - 1) for n >= 1, triangle read by rows.
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%I #11 Feb 06 2023 12:46:19

%S 1,-1,-1,1,1,0,-1,-1,0,1,1,0,0,-1,-1,0,0,1,1,0,0,0,-1,-1,0,0,0,1,1,0,

%T 0,0,0,-1,-1,0,0,0,0,1,1,0,0,0,0,0,-1,-1,0,0,0,0,0,1,1,0,0,0,0,0,0,-1,

%U -1,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,-1,-1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,-1,-1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0

%N Expansions of p(x,n)=(x^n - 1)*(x^(n + 1) - 1) for n >= 1, triangle read by rows.

%H Gareth Jones and David Singerman, <a href="https://doi.org/10.1112/blms/28.6.561">Belyi Functions, Hypermaps and Galois Groups</a>, Bull. London Math Soc. 28, (1996) pages 561-590 (dihedral group invariant on page 585).

%e {1, -1, -1, 1},

%e {1, 0, -1, -1, 0, 1},

%e {1, 0,0, -1, -1, 0, 0, 1},

%e {1, 0, 0, 0, -1, -1, 0, 0, 0, 1},

%e {1, 0, 0, 0, 0, -1, -1, 0, 0, 0, 0, 1},

%e {1, 0, 0, 0, 0, 0, -1, -1,0, 0, 0, 0, 0, 1},

%e {1, 0, 0, 0, 0, 0, 0, -1, -1, 0, 0, 0, 0, 0,0, 1},

%e {1, 0, 0, 0, 0, 0, 0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 1},

%e {1, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 1},

%e {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}

%t p[n_] = ExpandAll[(x^n - 1)*(x^(n + 1) - 1)];

%t a = Table[CoefficientList[p[n], x], {n, 1, 10}];

%t Flatten[a]

%K tabf,easy,less,sign

%O 1,1

%A _Roger L. Bagula_, Aug 24 2007