(Translated by https://www.hiragana.jp/)
# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a285183 Showing 1-1 of 1 %I A285183 #30 Apr 25 2024 09:11:54 %S A285183 0,2,2,2,1,6,1,2,2,5,1,6,1,5,4,2,1,6,1,5,4,4,1,6,1,4,2,5,1,11,1,2,3,4, %T A285183 3,6,1,4,3,5,1,11,1,4,4,4,1,6,1,5,3,4,1,6,3,5,3,4,1,11,1,4,4,2,3,10,1, %U A285183 4,3,9,1,6,1,4,4,4,3,10,1,5,2,4,1,11,3,4,3,4,1,11,3,4,3,4,3,6 %N A285183 Nearest integer to n*omega(n)/phi(n). %C A285183 n*omega(n)/phi(n) appears in certain bounds of Erdős for the Jacobsthal function g(n) (A048669). %D A285183 József Sándor, Dragoslav S. Mitrinovic, and Borislav Crstici, Handbook of Number Theory I, Springer Science & Business Media, 2005, Chapter I, p. 34, section I.32.3. %H A285183 Vincenzo Librandi, Table of n, a(n) for n = 1..10000 %H A285183 Paul Erdős, On the integers relatively prime to n and on a number theoretic function considered by Jacobsthal, Math. Scand., 10, 1962, 163-170. %p A285183 Digits:=30; %p A285183 A001221 := proc(n) nops(numtheory[factorset](n)) end proc: %p A285183 with(numtheory); %p A285183 f:=n->round(n*A001221(n)/phi(n)); %p A285183 t1:=[seq(f(n),n=1..130)]; %t A285183 Round[Table[(n PrimeNu[n] + 1/2)/EulerPhi[n], {n, 1, 100}]] (* _Vincenzo Librandi_, Apr 21 2017 - confirmed by _Giovanni Resta_ *) %o A285183 (Magma) [Round(n*#PrimeDivisors(n)/EulerPhi(n)): n in [1..100]] // _Vincenzo Librandi_, Apr 21 2017 %o A285183 (PARI) a(n) = {my(f = factor(n)); round(n*omega(f)/eulerphi(f));} \\ _Amiram Eldar_, Apr 25 2024 %Y A285183 Cf. A000010 (phi), A001221 (omega), A048669. %K A285183 nonn %O A285183 1,2 %A A285183 _N. J. A. Sloane_, Apr 19 2017 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE