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 A109607 #26 Nov 12 2023 08:48:39
%S A109607 0,0,0,2,3,9,5,20,15,26,19,54,23,77,41,59,63,135,53,170,79,125,109,
%T A109607 252,95,249,155,242,167,405,119,464,255,329,271,419,215,665,341,467,
%U A109607 319,819,251,902,439,539,505,1080,383,1028,499,815,623,1377,485,1099,671,1025
%N A109607 Sum of coprimes of n greater than 1.
%H A109607 Robert P. P. McKone, <a href="/A109607/b109607.txt">Table of n, a(n) for n = 0..14143</a>
%F A109607 a(n) = A023896(n) - 1. - _Joerg Arndt_, Mar 08 2013
%F A109607 G.f.: -x/(1 - x) + Sum_{k>=1} mu(k)*k*x^k/(1 - x^k)^3. - _Ilya Gutkovskiy_, May 28 2019
%e A109607 a(9) = 26 because 2,4,5,7,8 are coprime to 9 and 2+4+5+7+8 = 26.
%t A109607 a[n_] := Total@Select[Range[2, n], CoprimeQ[n, #] &]; Table[a[n], {n, 0, 57}] (* _Robert P. P. McKone_, Nov 12 2023 *)
%o A109607 (PARI) a(n) = sum(i=2, n-1, i*(gcd(i, n)==1)); \\ _Michel Marcus_, Mar 08 2013
%o A109607 (PARI) a(n)=if(n<3,0,n*eulerphi(n)/2-1) \\ _Charles R Greathouse IV_, Mar 08 2013
%Y A109607 Cf. A023896.
%K A109607 nonn,look
%O A109607 0,4
%A A109607 _Andrew Weimholt_, Jul 31 2005
%E A109607 Added "greater than 1" to name to match terms, _Joerg Arndt_, Mar 08 2013