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 A083266 #17 Apr 07 2021 15:06:50
%S A083266 1,3,6,10,15,17,28,30,39,37,66,51,91,65,83,94,153,92,190,121,157,145,
%T A083266 276,155,280,197,282,223,435,191,496,318,377,325,467,306,703,401,523,
%U A083266 409,861,347,946,523,617,577,1128,507,1085,592,887,721,1431,605,1171
%N A083266 Sum of related numbers (counted in A073757) belonging to n: a(n) = A000203(n) + A023896(n) - 1; related = {divisor-set, RRS}.
%C A083266 Sum of 1 <= m <= n such that gcd(m, n) is either 1 or m. - _Michael De Vlieger_, Apr 07 2021.
%H A083266 Michael De Vlieger, <a href="/A083266/b083266.txt">Table of n, a(n) for n = 1..10000</a>
%e A083266 n=10: related terms = {1,2,5,10,3,7,9}, sum = 1+2+5+10+1+3+7+9-1 = 37 = a(10).
%t A083266 Table[DivisorSigma[1, n] + Total@ Select[Range[2, n - 1], GCD[n, #] == 1 &], {n, 55}] (* or *)
%t A083266 {1}~Join~Array[DivisorSigma[1, #] + # EulerPhi[#]/2 - 1 &, 54, 2] (* _Michael De Vlieger_, Apr 07 2021 *)
%o A083266 (PARI) a(n)=if(n>1,sigma(n)+n*eulerphi(n)/2-1,1) \\ _Charles R Greathouse IV_, Feb 19 2013
%Y A083266 Cf. A073757 (count), A083267 (product), A083268 (lcm).
%K A083266 nonn,less
%O A083266 1,2
%A A083266 _Labos Elemer_, May 13 2003