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Number of primitive (aperiodic) palindromes using a maximum of five different symbols.
4

%I #16 Apr 24 2020 18:38:49

%S 5,0,20,20,120,100,620,600,3100,3000,15620,15480,78120,77500,390480,

%T 390000,1953120,1949900,9765620,9762480,48827480,48812500,244140620,

%U 244124400,1220703000,1220625000,6103512500,6103437480,30517578120,30517184400,152587890620,152587500000

%N Number of primitive (aperiodic) palindromes using a maximum of five 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 Sum_{d|n} mu(d)*A056451(n/d).

%o (PARI) a(n) = sumdiv(n, d, moebius(d)*5^((1 + n/d)\2));

%o for(n=1, 40, print1(a(n), ", ")); \\ _Petros Hadjicostas_, Apr 24 2020

%Y Cf. A056391, A056451.

%Y Column 5 of A284823.

%K nonn

%O 1,1

%A _Marks R. Nester_

%E More terms from _Petros Hadjicostas_, Apr 24 2020