cp's OEIS Frontend

A243283 One more than the partial sums of the characteristic function of A070003.

%I A243283 #18 Jul 18 2022 22:48:32
%S A243283 1,1,1,2,2,2,2,3,4,4,4,4,4,4,4,5,5,6,6,6,6,6,6,6,7,7,8,8,8,8,8,9,9,9,
%T A243283 9,10,10,10,10,10,10,10,10,10,10,10,10,10,11,12,12,12,12,13,13,13,13,
%U A243283 13,13,13,13,13,13,14,14,14,14,14,14,14,14,15,15,15,16
%N A243283 One more than the partial sums of the characteristic function of A070003.
%C A243283 a(n) tells how many positive integers <= n are divisible by the square of their largest noncomposite divisor. (This definition includes 1 as it is divisible by 1^2.)
%C A243283 a(n) = n - A243285(n).
%C A243283 a(1) = 1 and for all n > 1, a(A070003(n-1)) = n, thus this sequence works as an inverse function for the injection {a(1) = 1, a(n>1) = A070003(n-1)} (a sequence which is the union of {1} and A070003).
%H A243283 Antti Karttunen, <a href="/A243283/b243283.txt">Table of n, a(n) for n = 1..10000</a>
%o A243283 (Scheme, with memoizing macro definec from _Antti Karttunen_'s IntSeq-library)
%o A243283 (definec (A243283 n) (if (<= n 1) n (+ (A243283 (- n 1)) (if (zero? (A241917 n)) 1 0))))
%Y A243283 One more than A243282.
%Y A243283 Differs from A243284 for the first time at n=48. Here a(48)=10.
%Y A243283 Cf. A070003, A102354, A243285, A057627.
%K A243283 nonn
%O A243283 1,4
%A A243283 _Antti Karttunen_, Jun 02 2014