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 A335131 #9 May 24 2020 09:00:14
%S A335131 2,6,22,38,86,134,278,374,614,774,1254,1542,2118,2502,3526,4294,6022,
%T A335131 6886,8614,9574,12214,13974,17494,19414,23734,26326,32374,35062,41782,
%U A335131 45622,55222,60342,68022,72630,82998,90774,106326,113238,128598,136278,156438,166518
%N A335131 a(n) = Sum_{k=1..n} phi(k)*phi(k+1)*phi(k+2), where phi(k) = A000010(k) is Euler's totient function.
%H A335131 L. Mirsky, <a href="http://doi.org/10.1215/S0012-7094-49-01625-7">Summation formula involving arithmetic functions</a>, Duke Mathematical Journal, Vol. 16, No. 2 (1949), pp. 261-272.
%F A335131 a(n) ~ 3*c*n^4 / 8, where c = A206256 = Product_{p prime} (1 - 3/p^2) [Mirsky, 1949, p. 270, formula 30].
%t A335131 Accumulate[Table[EulerPhi[k]*EulerPhi[k+1]*EulerPhi[k+2], {k, 1, 50}]]
%o A335131 (PARI) a(n) = sum(k=1, n, eulerphi(k)*eulerphi(k+1)*eulerphi(k+2)); \\ _Michel Marcus_, May 24 2020
%Y A335131 Cf. A000010, A002088, A206256, A330319.
%K A335131 nonn
%O A335131 1,1
%A A335131 _Vaclav Kotesovec_, May 24 2020