cp's OEIS Frontend

A070296 Let sphi(k) = number of primes less than k and coprime to it (A048865); then a(n) = number of integers m with sphi(m) = n.

%I A070296 #10 Jul 03 2025 18:23:07
%S A070296 2,3,2,4,3,3,4,5,3,5,6,1,4,5,8,2,5,4,3,5,4,7,7,5,2,3,3,6,10,5,7,2,10,
%T A070296 3,4,7,5,4,7,4,7,3,5,2,12,10,5,3,4,5,2,10,6,7,5,3,5,4,4,9,14,3,3,5,12,
%U A070296 8,7,3,5,7,6,7,5,5,6,7,6,9,7,4,7,5,5,3,8,7,3,2,7,10,7,7,4,7,7
%N A070296 Let sphi(k) = number of primes less than k and coprime to it (A048865); then a(n) = number of integers m with sphi(m) = n.
%F A070296 a(n) = number of m such that A048865(m) = n.
%e A070296 a(4) = 3. The three values of m for which sphi(m) = 4 are 11, 14 and 15. The coprime primes less than 11 are 2, 3, 5 and 7. The coprime primes less than 14 are 3, 5, 11 and 13. The coprime primes less than 15 are 2, 7, 11 and 13.
%t A070296 (continuing from A048865) Table[Count[t, i], {i, 0, 150}]
%K A070296 nonn
%O A070296 0,1
%A A070296 _Amarnath Murthy_, May 10 2002
%E A070296 More terms from _Hans Havermann_, Jun 04 2002