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%I #22 Feb 18 2024 18:27:11
%S 2,0,2,2,6,4,14,12,28,24,62,54,126,112,246,240,510,476,1022,990,2030,
%T 1984,4094,4020,8184,8064,16352,16254,32766,32484,65534,65280,131006,
%U 130560,262122,261576,524286,523264,1048446,1047540,2097150,2094988,4194302,4192254
%N Number of primitive (aperiodic) palindromes using a maximum of two different symbols.
%D M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
%F a(n) = Sum_{d|n} mu(d)*A016116(1 + n/d).
%o (PARI) a(n) = sumdiv(n, d, moebius(d)*2^((1 + n/d)\2)); \\ _Michel Marcus_, Apr 24 2020
%o (Python)
%o from sympy import mobius, divisors
%o def A056458(n): return sum(mobius(n//d)<<(1+d>>1) for d in divisors(n, generator=True)) # _Chai Wah Wu_, Feb 18 2024
%Y Cf. A016116.
%Y Column 2 of A284823.
%K nonn
%O 1,1
%A _Marks R. Nester_
%E More terms from _Michel Marcus_, Apr 24 2020
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