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%I #62 Dec 13 2023 08:45:03
%S 2,2,2,2,2,11,59,577,13999,232988779,7616971,141695022522269,
%T 52247207549418855988531757,
%U 784710183186946763762727466890094566789132493,2696635801755076542772762485782137063037806561559423,406892172682482048521833925827793697965504908008299460763
%N a(1)=a(2)=a(3)=a(4)=a(5)=2; thereafter, a(n) = gpf(1 + Product_{k=1..5} a(n-k)), where gpf is greatest prime factor.
%H Charles R Greathouse IV, <a href="/A260725/b260725.txt">Table of n, a(n) for n = 1..18</a>
%H Anders Hellström, <a href="/A260725/a260725_1.txt">Sage program</a>
%o (PARI) gpf(n)=my(v=factor(n)[, 1]); v[#v];
%o first(m)=my(v=[2, 2, 2, 2, 2], f=5);print1("2,2,2,2,2"); if(m>f, for(i=f+1, m, p=prod(j=1, f, v[i-j]) ; v=concat(v, gpf(p+1));print1(" ,",v[i]); )); v
%Y Cf. A259828, A000945.
%K nonn
%O 1,1
%A _Anders Hellström_, Jul 30 2015
%E a(15) from _Charles R Greathouse IV_, Aug 06 2015
%E a(16) from _Charles R Greathouse IV_, Aug 10 2015
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