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%I #19 Mar 03 2023 09:31:36
%S 1,5,19,59,165,419,1001,2257,4877,10133,20399,39881,76085,141877,
%T 259373,465493,821813,1428725,2449573,4145249,6931259,11459483,
%U 18749007,30373189,48752125,77568683,122406223,191651957,297856813,459652759,704595749,1073152385
%N a(n) = A120963(2*n+1)/2.
%C A bisection of A341710.
%H D. Weigel, R. Veysseyre, T. Phan, J. M. Effantin, and Y. Billiet, <a href="https://doi.org/10.1107/S0108767384000702">Crystallography, geometry and physics in higher dimensions. I. Point-symmetry operations</a>, Acta Cryst., A40 (1984), 323-330 (see Table 3).
%p with(numtheory):
%p b:= proc(n) option remember; nops(invphi(n)) end:
%p g:= proc(n) option remember; `if`(n=0, 1, add(
%p g(n-j)*add(d*b(d), d=divisors(j)), j=1..n)/n)
%p end:
%p a:= n-> g(2*n+1)/2:
%p seq(a(n), n=0..40); # _Alois P. Heinz_, Feb 19 2021
%t terms = 64; (* number of terms of A120963 *)
%t nmax = Floor[terms/2] - 1;
%t S[m_] := S[m] = CoefficientList[Product[1/(1 - x^EulerPhi[k]),
%t {k, 1, m*terms}] + O[x]^(terms + 1),x];
%t S[m = 1];
%t S[m++];
%t While[S[m] != S[m - 1], m++];
%t A120963 = S[m];
%t a[n_ /; 0 <= n <= nmax] := A120963[[2 n + 2]]/2;
%t Table[a[n], {n, 0, nmax}] (* _Jean-François Alcover_, May 12 2022 *)
%Y Cf. A120963, A341710, A341712.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Feb 19 2021
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