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 A091371 #13 Feb 20 2025 19:46:10 %S A091371 1,1,2,0,4,0,6,-1,1,0,10,-1,12,0,1,-2,16,-1,18,-1,1,0,22,-2,3,0,0,-1, %T A091371 28,-1,30,-3,1,0,3,-2,36,0,1,-2,40,-1,42,-1,0,0,46,-3,5,-1,1,-1,52,-2, %U A091371 3,-2,1,0,58,-2,60,0,0,-4,3,-1,66,-1,1,-1,70,-3,72,0,0,-1,5,-1,78,-3 %N A091371 Smallest prime factor of n - number of prime factors of n with multiplicity. %C A091371 a(n) = A020639(n) - A001222(n). %C A091371 a(A091375(n)) < 0. a(A091376(n)) = 0. a(A091377(n)) > 0. %H A091371 Harvey P. Dale, <a href="/A091371/b091371.txt">Table of n, a(n) for n = 1..1000</a> %p A091371 with(numtheory); A091371:=n->`if`(n=1,1,min(op(factorset(n)))-bigomega(n)); seq(A091371(k), k=1..100); # _Wesley Ivan Hurt_, Oct 27 2013 %t A091371 Array[FactorInteger[#][[1,1]]-PrimeOmega[#]&,80] (* _Harvey P. Dale_, May 25 2012 *) %Y A091371 Cf. A020639 (lpf), A001222 (Omega). %Y A091371 Cf. A091372, A091373, A091374, A091375, A091376, A091377. %K A091371 sign %O A091371 1,3 %A A091371 _Reinhard Zumkeller_, Jan 04 2004 %E A091371 Definition clarified by _Harvey P. Dale_, May 25 2012