A143481 - OEIS

%I #30 Oct 12 2015 22:27:43

%S 1,2,6,8,20,24,42,48,54,64,110,112,120,132,144,160,192,216,288,320,

%T 324,360,396,416,440,480,486,504,616,624,660,672,720,736,840,864,1008,

%U 1044,1104,1120,1200,1224,1260,1280,1296,1320,1380,1408,1512,1560,1632,1680

%N a(n) = phi(A143480(n)) where phi(m) = A000010(m).

%C Previous name was: a(n) is the number of positive integers <= A143480(n) and coprime to A143480(n).

%C a(n+1) > a(n) for all n.

%H Ivan Neretin and Peter Kagey, <a href="/A143481/b143481.txt">Table of n, a(n) for n = 1..10000</a>, first 1000 terms from Ivan Neretin

%F a(n) = phi(A143480(n)) = A000010(A143480(n)).

%p A[1]:= 1:

%p for n from 2 to 100 do

%p   for k from n by n do

%p      r:= numtheory:-phi(k);

%p      if r > A[n-1] then

%p         A[n]:= r;

%p         break

%p      fi

%p   od:

%p od:

%p seq(A[i], i=1..100); # _Robert Israel_, Sep 04 2015

%t a = b = {1}; Do[k = 1; While[(r = EulerPhi[nxt = k*n]) <= b[[-1]], k++]; AppendTo[a, nxt]; AppendTo[b, r], {n, 2, 52}]; b (* _Ivan Neretin_, May 25 2015 *)

%Y Cf. A143480.

%Y A143483 is an analogous sequence with A143482 as the referenced sequence.

%K nonn

%O 1,2

%A _Leroy Quet_, Aug 19 2008

%E Extended by _Ray Chandler_, Nov 09 2008

%E Name changed by _Peter Kagey_, Sep 03 2015