|
%I #11 Dec 18 2014 02:04:39
%S 1,1,1,2,1,2,1,3,2,2,1,2,1,3,2,2,1,3,1,3,2,2,1,2,3,4,2,3,1,2,1,5,3,2,
%T 3,2,1,3,6,2,1,2,1,3,2,3,1,4,2,3,2,2,1,2,2,3,2,3,1,3,1,4,4,2,3,2,1,5,
%U 2,2,1,4,1,4,2,2,3,3,1,3,3,2,1,2,4,3,2,3,1,2,2,5,3,3,3,2,1,3,2,2,1,4,1,3,3,2,1,5,1,4,3,2,1,2,2,3,2,3,4,2
%N a(n) = smallest positive integer k such that A083221(k, n) has at most two prime factors (is a prime or semiprime).
%C Records occur at 1, 4, 8, 26, 32, 39, 238, 462, 1075, 1763, ... with record values 1, 2, 3, 4, 5, 6, 8, 9, 11, 13, ...
%C New distinct values occur at 1, 4, 8, 26, 32, 39, 238, 306, 462, 1075, 1106, 1763, ... with the values 1, 2, 3, 4, 5, 6, 8, 7, 9, 11, 10, 13, ...
%H Antti Karttunen, <a href="/A251717/b251717.txt">Table of n, a(n) for n = 1..2518</a>
%F For all n, a(n) <= A251718(n) <= A251719(n).
%o (Scheme) (define (A251717 n) (let loop ((i 1)) (if (<= (A001222 (A083221bi i n)) 2) i (loop (+ i 1))))) ;; Code for A083221bi given in A083221.
%Y Variant: A251718.
%Y The positions of ones: A008578.
%Y Cf. A001222, A083221 (A083140), A251719.
%Y a(n+1) differs from A057217(n-1) for the first time at n=19, where a(20) = 3, while A057217(18) = 4.
%K nonn
%O 1,4
%A _Antti Karttunen_, Dec 15 2014
|
