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 A260723 #7 Aug 10 2015 07:28:20 %S A260723 1,1,2,2,4,2,4,6,2,4,8,4,2,4,6,8,6,4,6,6,6,2,6,10,8,4,2,6,4,12,6,8,4, %T A260723 12,2,4,2,12,16,2,10,2,4,6,2,4,8,10,8,12,6,4,14,6,6,16,2,6,4,12,6,2, %U A260723 16,6,6,8,10,8,4,2,10,2,4,8,18,4,8,6,12,4,6,6,8,10,8,6,12,12,12,4,12,2,12,6,4,8,18,4,6,6,8,6,12,6,6,6,4,20,6 %N A260723 First differences of Ludic numbers: a(n) = A003309(n+1) - A003309(n). %H A260723 Antti Karttunen, <a href="/A260723/b260723.txt">Table of n, a(n) for n = 1..10000</a> %H A260723 <a href="/index/Si#sieve">Index entries for sequences generated by sieves</a> %F A260723 a(n) = A003309(n+1) - A003309(n). %o A260723 (Scheme) (define (A260723 n) (- (A003309 (+ n 1)) (A003309 n))) %Y A260723 Cf. A003309. %Y A260723 Cf. also A001223, A031883, A260722. %K A260723 nonn %O A260723 1,3 %A A260723 _Antti Karttunen_, Aug 06 2015