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 A080847 #17 May 17 2025 05:44:14 %S A080847 3,1,1,2,1,3,1,2,2,3,1,2,1,3,3,2,1,2,1,2,3,3,1,2,2,3,2,2,1,1,1,2,3,3, %T A080847 3,2,1,3,3,2,1,1,1,2,2,3,1,2,2,2,3,2,1,2,3,2,3,3,1,2,1,3,2,2,3,1,1,2, %U A080847 3,1,1,2,1,3,2,2,3,1,1,2,2,3,1,2,3,3,3,2,1,2,3,2,3,3,3,2,1,2,2,2,1,1,1,2,1 %N A080847 a(n) = mu(n)+2, where mu is the Moebius function (A008683). %H A080847 Antti Karttunen, <a href="/A080847/b080847.txt">Table of n, a(n) for n = 1..5000</a> %H A080847 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>. %F A080847 1 <= a(n) <= 3. %t A080847 MoebiusMu[Range[120]]+2 (* _Harvey P. Dale_, Dec 31 2021 *) %o A080847 (Scheme) (define (A080847 n) (+ 2 (A008683 n))) ;; _Antti Karttunen_, Jul 26 2017 %o A080847 (PARI) a(n) = moebius(n) + 2; \\ _Amiram Eldar_, May 17 2025 %Y A080847 Cf. A008683, one more than A007423, one less than A231821. %Y A080847 Cf. A080848, A080849. %K A080847 nonn,easy %O A080847 1,1 %A A080847 _Reinhard Zumkeller_, Feb 20 2003