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 A133829 #12 Mar 02 2023 15:58:35
%S A133829 2,2,3,2,2,4,2,2,3,5,2,4,2,2,6,2,2,4,2,5,7,2,2,4,2,2,3,8,2,6,2,2,3,2,
%T A133829 2,9,2,2,3,5,2,7,2,2,10,2,2,4,2,5,3,2,2,4,11,8,3,2,2,6,2,2,7,2,2,12,2,
%U A133829 2,3,5,2,9,2,2,6,2,2,13,2,5,3,2,2,8,2,2,3,2,2,10,14,2,3,2,2,4,2,2,3
%N A133829 a(n) = the largest "non-isolated divisor" of 2n. A positive divisor k of n is non-isolated if k-1 or k+1 also divides n.
%C A133829 No odd integer has any non-isolated divisors.
%H A133829 Antti Karttunen, <a href="/A133829/b133829.txt">Table of n, a(n) for n = 1..20000</a>
%p A133829 A133829 := proc(n) local divs,k,i ; divs := sort(convert(numtheory[divisors](2*n),list)) ; for i from 1 to nops(divs) do k := op(-i,divs) ; if k-1 in divs or k+1 in divs then RETURN(k) ; fi ; od: RETURN(0) ; end: seq(A133829(n),n=1..100) ; # _R. J. Mathar_, Oct 19 2007
%o A133829 (PARI) A133829(n) = { n = 2*n; my(m=0); fordiv(n,d,if(!(n%(1+d)) || ((d>1) && !(n%(d-1))), m = max(m,d))); (m); }; \\ _Antti Karttunen_, Mar 02 2023
%Y A133829 Cf. A133780, A133828.
%K A133829 nonn
%O A133829 1,1
%A A133829 _Leroy Quet_, Sep 25 2007
%E A133829 More terms from _R. J. Mathar_, Oct 19 2007