A171989 - OEIS

%I #13 Nov 30 2024 06:26:54

%S 1,2,6,30,210,2310,29464,476928,9671392,222388792,6438663000,

%T 200560490130,7379606916000,299261862900000,13004421443456272,

%U 614231422273479360,31727029501157817600,1915248189055217892480,116762424492324428512272

%N a(n) = A000010(A006862(n)).

%H Amiram Eldar, <a href="/A171989/b171989.txt">Table of n, a(n) for n = 0..98</a>

%p A006862 := proc(n) if n = 0 then 2; else 1+mul(ithprime(j),j=1..n) ; end if: end proc: A171989 := proc(n) numtheory[phi](A006862(n)) ; end proc: seq(A171989(n),n=1..18) ; # _R. J. Mathar_, Jan 30 2010

%o (PARI) a(n)=eulerphi(prod(i=1,n,prime(i))+1) \\ _Charles R Greathouse IV_, Mar 05 2013

%Y Cf. A000010, A006862.

%K nonn

%O 0,2

%A _Giovanni Teofilatto_, Jan 21 2010

%E a(1) inserted and extended beyond a(5) by _R. J. Mathar_, Jan 30 2010

%E Offset changed to 0 and a(0) prepended by _Amiram Eldar_, Nov 30 2024