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 A203908 #38 Jan 14 2023 07:15:27
%S A203908 1,1,2,0,4,2,6,1,1,4,10,0,12,6,8,2,16,1,18,0,12,10,22,2,3,12,0,0,28,8,
%T A203908 30,3,20,16,24,0,36,18,24,4,40,12,42,0,4,22,46,4,5,3,32,0,52,0,40,6,
%U A203908 36,28,58,0,60,30,6,4,48,20,66,0,44,24,70,1,72,36
%N A203908 Multiplicative with a(p^e) = abs(p-e).
%C A203908 Density of nonzero terms is 0.85317570460439... = Product(1 - p^-p + p^-(p+1)) where p runs over the primes. - _Charles R Greathouse IV_, Jan 23 2012 [corrected by _Amiram Eldar_, Jan 14 2023]
%H A203908 Reinhard Zumkeller, <a href="/A203908/b203908.txt">Table of n, a(n) for n = 1..10000</a>
%H A203908 Vaclav Kotesovec, <a href="/A203908/a203908.jpg">Plot of Sum_{k=1..n} a(k) / n^2 for n = 1..1000000</a>
%F A203908 Sum_{k=1..n} a(k) ~ c * n^2, where c = (Pi^4/72) * Product_{p prime} ((1 - 1/p^5 + 2/p^4 + 2/p^3 - 4/p^2)*(1 - p - 3*p^2 + p^3 + p^4 + 2*p^(2-2*p))/(1 - p - 3*p^2 + p^3 + p^4)) = 0.2228124152... . - _Amiram Eldar_, Jan 14 2023
%t A203908 ar[p_,s_] := Abs[p-s]; arit[1] = 1; arit[n_] := Product[ar[FactorInteger[n][[i,1]], FactorInteger[n][[i,2]]], {i, Length[FactorInteger[n]]}]; Array[arit, 100] (* _José María Grau Ribas_, Jan 25 2012 *)
%o A203908 (Haskell)
%o A203908 a203908 n = product $ map abs $
%o A203908 zipWith (-) (a027748_row n) (a124010_row n)
%o A203908 -- _Reinhard Zumkeller_, Dec 24 2013
%Y A203908 Cf. A100717 (n such that a(n)=0).
%Y A203908 Cf. A008473, A027748, A124010.
%K A203908 nonn,mult
%O A203908 1,3
%A A203908 _José María Grau Ribas_, Jan 07 2012