cp's OEIS Frontend

A281793 The largest prime factor of (1+n)*(1+n^2).

%I A281793 #15 Sep 08 2022 08:46:18
%S A281793 1,2,5,5,17,13,37,5,13,41,101,61,29,17,197,113,257,29,19,181,401,17,
%T A281793 97,53,577,313,677,73,157,421,53,37,41,109,89,613,1297,137,17,761,
%U A281793 1601,29,353,37,149,1013,73,17,461,1201,61,1301,541,281,2917,89,3137,29
%N A281793 The largest prime factor of (1+n)*(1+n^2).
%H A281793 Vincenzo Librandi, <a href="/A281793/b281793.txt">Table of n, a(n) for n = 0..1000</a>
%F A281793 a(n) = max( A006530(n+1), A014442(n)).
%F A281793 a(n) = A006530(A281660(n)).
%p A281793 A281793 := proc(n)
%p A281793     A006530((1+n)*(1+n^2)) ;
%p A281793 end proc:
%p A281793 seq(A281793(n),n=0..60) ;
%t A281793 Table[Max[Transpose[FactorInteger[(1 + n) (1 + n^2)]][[1]]], {n, 0, 60}] (* _Vincenzo Librandi_, Jun 03 2017 *)
%o A281793 (Magma) [#f eq 0 select 1 else f[ #f][1] where f is Factorization((1+n)*(1+n^2)): n in [0..60]]; // _Vincenzo Librandi_, Jun 03 2017
%o A281793 (PARI) a(n) = if (n==0, 1, my(f=factor((1+n)*(1+n^2))); vecmax(f[, 1])); \\ _Michel Marcus_, Jun 03 2017; corrected Jun 13 2022
%Y A281793 Cf. A006530, A014442, A281660.
%K A281793 nonn,easy
%O A281793 0,2
%A A281793 _R. J. Mathar_, Jan 30 2017