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 A277455 #18 Oct 17 2016 16:37:56
%S A277455 0,0,1,4,6,10,20,1,36,172,2192,3371,1,22327,135561,517656,284492,
%T A277455 933118,5446991,24265724,18238138,93800069,334654476,1368408363,
%U A277455 2584589232,1823879615,25669818480,41583822879,1967330543,29409700520,1265785403,3239855363874
%N A277455 Arithmetic derivatives of the Motzkin numbers.
%F A277455 a(n) = A003415(A001006(n)).
%F A277455 a(n) = 1 for n in A092831.
%t A277455 Table[If[Abs@ # < 2, 0, # Total[#2/#1 & @@@ FactorInteger[Abs@ #]]] &@ Hypergeometric2F1[(1 - n)/2, -n/2, 2, 4], {n, 0, 31}] (* _Michael De Vlieger_, Oct 17 2016, after _Michael Somos_ at A003415 and _Peter Luschny_ at A001006 *)
%Y A277455 Cf. A003415, A001006, A068329, A092831.
%K A277455 nonn
%O A277455 0,4
%A A277455 _Paul Bedard_, Oct 16 2016
%E A277455 More terms from _Alois P. Heinz_, Oct 16 2016