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 A073757 #33 Nov 25 2021 12:43:10 %S A073757 1,2,3,4,5,5,7,7,8,7,11,9,13,9,11,12,17,11,19,13,15,13,23,15,22,15,21, %T A073757 17,29,15,31,21,23,19,27,20,37,21,27,23,41,19,43,25,29,25,47,25,44,25, %U A073757 35,29,53,25,43,31,39,31,59,27,61,33,41,38,51,27,67,37,47,31,71,35,73 %N A073757 a(n) = d(n) + phi(n) - 1. %C A073757 Old name was: Number of numbers "related" to n: either divisors or terms in RRS of n. %C A073757 RRS of n means reduced residue system modulo n. One considers here the smallest positive one. - _Wolfdieter Lang_, Jan 16 2016 %H A073757 Antti Karttunen, <a href="/A073757/b073757.txt">Table of n, a(n) for n = 1..10000</a> %F A073757 a(n) = n - A045763(n) = A000005(n) + A000010(n) - 1. %F A073757 If p is prime then a(p) = p. %F A073757 Row sums of triangle A134673. - _Gary W. Adamson_, Nov 05 2007 %t A073757 DivisorSigma[0, #] + EulerPhi[#] - 1 & /@ Range[73] (* _Jayanta Basu_, Jul 09 2013 *) %o A073757 (PARI) a(n)=my(f=factor(n)); numdiv(f)+eulerphi(f)-1 \\ _Charles R Greathouse IV_, Nov 14 2014 %Y A073757 Cf. A000005 (tau), A000010 (phi), A045763, A134673. %K A073757 nonn,easy %O A073757 1,2 %A A073757 _Labos Elemer_, Aug 08 2002 %E A073757 Replaced Name with formula. - _Wesley Ivan Hurt_, Nov 24 2021