This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A251717 #11 Dec 18 2014 02:04:39 %S A251717 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 A251717 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 A251717 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 A251717 a(n) = smallest positive integer k such that A083221(k, n) has at most two prime factors (is a prime or semiprime). %C A251717 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 A251717 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 A251717 Antti Karttunen, <a href="/A251717/b251717.txt">Table of n, a(n) for n = 1..2518</a> %F A251717 For all n, a(n) <= A251718(n) <= A251719(n). %o A251717 (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 A251717 Variant: A251718. %Y A251717 The positions of ones: A008578. %Y A251717 Cf. A001222, A083221 (A083140), A251719. %Y A251717 a(n+1) differs from A057217(n-1) for the first time at n=19, where a(20) = 3, while A057217(18) = 4. %K A251717 nonn %O A251717 1,4 %A A251717 _Antti Karttunen_, Dec 15 2014