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 A067541 phi(n*(n+1)/2)/phi(n) where phi is the Euler totient function A000010(n). 1
 1, 2, 1, 2, 2, 6, 2, 3, 4, 10, 2, 6, 6, 8, 4, 8, 6, 18, 4, 6, 10, 22, 4, 10, 12, 18, 6, 14, 8, 30, 8, 10, 16, 24, 6, 18, 18, 24, 8, 20, 12, 42, 10, 12, 22, 46, 8, 21, 20, 32, 12, 26, 18, 40, 12, 18, 28, 58, 8, 30, 30, 36, 16, 24, 20, 66, 16, 22, 24, 70, 12, 36, 36, 40, 18, 30, 24 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 FORMULA Let n = 2^k*m, GCD(m, 2) = 1. Then a(n) = phi((n + 1)/2) if k = 0, phi(n + 1) if k = 1 and (phi(n + 1))/2 if k > 1. - Vladeta Jovovic, Feb 06 2002 a(n) = A000010(A000217(n))/A000010(n). - Michel Marcus, Nov 04 2013 EXAMPLE a(6) = 6; phi(6*7/2)/phi(6) = phi(21)/phi(6) = 12/2 = 6. MAPLE with(numtheory); A067541:=n->phi(n*(n+1)/2)/phi(n); seq(A067541(k), k=1..100); # Wesley Ivan Hurt, Nov 04 2013 MATHEMATICA Table[EulerPhi[n*(n+1)/2]/EulerPhi[n], {n, 1, 100}] (* Vincenzo Librandi, Mar 05 2013 *) PROG (PARI) a(n)=eulerphi(n*(n+1)/2)/eulerphi(n) \\ Charles R Greathouse IV, Mar 05 2013 (Magma) [EulerPhi(n*(n+1) div 2)/EulerPhi(n): n in [1..100]]; // Vincenzo Librandi, Mar 05 2013 CROSSREFS Sequence in context: A093659 A306714 A200745 * A054706 A351082 A334500 Adjacent sequences: A067538 A067539 A067540 * A067542 A067543 A067544 KEYWORD nonn AUTHOR Benoit Cloitre, Jan 28 2002 STATUS approved

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Last modified June 2 18:52 EDT 2023. Contains 363100 sequences. (Running on oeis4.)