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 A119288 #19 Mar 31 2023 14:14:43
%S A119288 1,1,1,1,1,3,1,1,1,5,1,3,1,7,5,1,1,3,1,5,7,11,1,3,1,13,1,7,1,3,1,1,11,
%T A119288 17,7,3,1,19,13,5,1,3,1,11,5,23,1,3,1,5,17,13,1,3,11,7,19,29,1,3,1,31,
%U A119288 7,1,13,3,1,17,23,5,1,3,1,37,5,19,11,3,1,5,1,41,1,3,17,43,29,11,1,3,13,23
%N A119288 a(n) is the second smallest prime factor of n, or 1 if n is a prime power.
%C A119288 Least prime factor of {n divided by the maximal power of the least prime factor of n}. - after the original name of the sequence.
%C A119288 a(n) = A020639(A028234(n)).
%C A119288 a(n) = 1 iff n is a prime power: a(A000961(n))=1 and a(A024619(n))>1.
%H A119288 Antti Karttunen, <a href="/A119288/b119288.txt">Table of n, a(n) for n = 1..10000</a>
%F A119288 A010055(n) = 0^(a(n)-1). - _Reinhard Zumkeller_, May 13 2006
%t A119288 Join[{1},Table[Which[PrimePowerQ[n],1,True,FactorInteger[n][[2,1]]],{n,2,100}]] (* _Harvey P. Dale_, Feb 08 2020 *)
%o A119288 (PARI) a(n) = if (isprimepower(n) || (n==1), 1, my(f=factor(n)[,1]); f[2]); \\ _Michel Marcus_, Mar 01 2023
%o A119288 (Python)
%o A119288 from sympy import primefactors
%o A119288 def A119288(n): return 1 if len(s:=primefactors(n)) <= 1 else sorted(s)[1] # _Chai Wah Wu_, Mar 31 2023
%Y A119288 Cf. A014673, A020639, A028234, A292269.
%K A119288 nonn
%O A119288 1,6
%A A119288 _Reinhard Zumkeller_, May 13 2006
%E A119288 Name changed by _Antti Karttunen_, Oct 04 2017