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 A052248 #20 May 16 2020 14:46:14 %S A052248 2,3,5,3,7,3,11,13,5,17,19,7,23,17,29,5,31,23,3,37,41,43,47,11,17,53, %T A052248 3,37,61,43,67,23,73,5,31,79,83,43,89,5,61,3,97,11,103,109,113,19,29, %U A052248 79,5,83,127,131,89,5,137,139,47,97,151,103,13,157,163,167,173,29,13 %N A052248 Greatest prime divisor of all composite numbers between p and next prime. %C A052248 Or, largest of all prime factors of the numbers between prime(n) and prime(n+1). %C A052248 a(n) = 3, 5, 7, 11, 13 iff prime(n) is in A059960, A080185, A080186, A080187, A080188 respectively. This sequence defines a mapping f of primes > 2 to primes (cf. A080189) and f(p) < p holds for all p > 2. - _Klaus Brockhaus_, Feb 10 2003 %C A052248 a(n) = A006530(A061214(n)). - _Reinhard Zumkeller_, Jun 22 2011 %H A052248 T. D. Noe, <a href="/A052248/b052248.txt">Table of n, a(n) for n = 2..1000</a> %F A052248 a(n) = max(prime(n) < k < prime(n+1), A006530(k)). %e A052248 a(8) = 11 since 20 = 2*2*5, 21 = 3*7, 22 = 2*11 are the numbers between prime(8) = 19 and prime(9) = 23. %e A052248 For n=9, n-th prime is 23, composites between 23 and next prime are 24 25 26 27 29 of which largest prime divisor is 13, so a(9)=13. %t A052248 g[n_] := Block[{t = Range[Prime[n] + 1, Prime[n + 1] - 1]}, Max[First /@ Flatten[ FactorInteger@t, 1]]]; Table[ g[n], {n, 2, 72}] (* _Robert G. Wilson v_, Feb 08 2006 *) %t A052248 cmp[{a_,b_}]:=Max[Flatten[FactorInteger/@Range[a+1,b-1],1][[All,1]]]; cmp/@ Partition[ Prime[Range[2,80]],2,1] (* _Harvey P. Dale_, May 16 2020 *) %o A052248 (PARI) forprime(p=3,360,q=nextprime(p+1); m=0; for(j=p+1,q-1,f=factor(j); a=f[matsize(f)[1],1]; if(m<a,m=a)); print1(m,",")) %o A052248 (Haskell) %o A052248 a052248 n = a052248_list !! (n-2) %o A052248 a052248_list = f a065091_list where %o A052248 f (p:ps'@(p':ps)) = (maximum $ map a006530 [p+1..p'-1]) : f ps' %o A052248 -- _Reinhard Zumkeller_, Jun 22 2011 %Y A052248 Cf. A006530, A059960, A080185, A080186, A080187, A080188, A080189, A052180, A065091. %K A052248 nonn,easy,nice %O A052248 2,1 %A A052248 _N. J. A. Sloane_