This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A056461 #16 Apr 24 2020 18:38:49
%S A056461 5,0,20,20,120,100,620,600,3100,3000,15620,15480,78120,77500,390480,
%T A056461 390000,1953120,1949900,9765620,9762480,48827480,48812500,244140620,
%U A056461 244124400,1220703000,1220625000,6103512500,6103437480,30517578120,30517184400,152587890620,152587500000
%N A056461 Number of primitive (aperiodic) palindromes using a maximum of five different symbols.
%D A056461 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 A056461 Sum_{d|n} mu(d)*A056451(n/d).
%o A056461 (PARI) a(n) = sumdiv(n, d, moebius(d)*5^((1 + n/d)\2));
%o A056461 for(n=1, 40, print1(a(n), ", ")); \\ _Petros Hadjicostas_, Apr 24 2020
%Y A056461 Cf. A056391, A056451.
%Y A056461 Column 5 of A284823.
%K A056461 nonn
%O A056461 1,1
%A A056461 _Marks R. Nester_
%E A056461 More terms from _Petros Hadjicostas_, Apr 24 2020