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Greatest prime factor of pyramidal number A000292(n).
1

%I #11 Feb 17 2023 07:40:11

%S 2,5,5,7,7,7,5,11,11,13,13,13,7,17,17,19,19,19,11,23,23,23,13,13,13,

%T 29,29,31,31,31,17,17,17,37,37,37,19,41,41,43,43,43,23,47,47,47,7,17,

%U 17,53,53,53,11,19,29,59,59,61,61,61,31,13,13,67,67,67,23,71,71,73,73,73,37

%N Greatest prime factor of pyramidal number A000292(n).

%C a(n) <= n+2, with equality if n+2 is prime. - _Robert Israel_, Feb 16 2023

%H Robert Israel, <a href="/A121359/b121359.txt">Table of n, a(n) for n = 2..10000</a>

%F a(n) = A006530(A000292(n)).

%p f:= n -> max(numtheory:-factorset(n*(n+1)*(n+2)/6)):

%p map(f, [$2..100]); # _Robert Israel_, Feb 16 2023

%t FactorInteger[#][[-1,1]]&/@Binomial[Range[2,80]+2,3] (* _Harvey P. Dale_, Jan 31 2013 *)

%Y Cf. A000292, A006530.

%K nonn

%O 2,1

%A _Zak Seidov_, Sep 06 2006

%E Offset corrected by _Robert Israel_, Feb 16 2023