A098802 - OEIS

%I #13 Sep 15 2021 05:44:49

%S 1,1,1,1,2,1,1,3,3,1,1,2,3,2,1,1,5,5,5,5,1,1,3,5,5,5,3,1,1,7,7,7,7,7,

%T 7,1,1,2,7,7,7,7,7,2,1,1,3,3,7,7,7,7,3,3,1,1,5,5,5,7,7,7,5,5,5,1,1,11,

%U 11,11,11,11,11,11,11,11,11,1,1,3,11,11,11,11,11,11,11,11,11,3,1

%N Greatest prime factors in Pascal's triangle (read by rows).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PascalsTriangle.html">Pascal's Triangle</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GreatestPrimeFactor.html">Greatest Prime Factor</a>

%H <a href="/index/Pas#Pascal">Index entries for triangles and arrays related to Pascal's triangle</a>

%F T(n,k) = A006530(A007318(n,k)), 0<=k<=n.

%F For primes p and k<p: T(p,k)=p (k>0), T(p+1,k)=p (k>1) and T(n,k)<p for n<p.

%t T[n_, k_] := FactorInteger[Binomial[n, k]][[-1, 1]];

%t Table[T[n, k], {n, 0, 13}, {k, 0, n}] // Flatten (* _Jean-François Alcover_, Sep 15 2021 *)

%Y Cf. A006530, A007318.

%K nonn,tabl

%O 0,5

%A _Reinhard Zumkeller_, Nov 01 2004