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A258581 a(1) = 2; for n > 1 if n is even a(n) = gpf(1 + Product_{odd m,m<n}a(m)), while if n is odd a(n) = gpf(1 + Product_{even m,m<n}a(m)). 3

%I

%S 2,3,2,5,2,3,23,37,17,149,761,50647,4799,411527,18871308021859,

%T 10312625105789,17838863896549,57892815889963361050999657943,

%U 2252973546284243766517,1849093263449444009859625443689931115519009693

%N a(1) = 2; for n > 1 if n is even a(n) = gpf(1 + Product_{odd m,m<n}a(m)), while if n is odd a(n) = gpf(1 + Product_{even m,m<n}a(m)).

%H Anders Hellström, <a href="https://oeis.org/wiki/User:Anders_Hellstr%C3%B6m/A258581.sage">Sage program</a>

%H Anders Hellström, <a href="https://oeis.org/wiki/User:Anders_Hellstr%C3%B6m/A258581.m">Mercury program</a>

%o (PARI) gpf(n)=my(v=factor(n)[, 1]); v[#v];

%o main(size)=my(v=vector(size), i, odd=2, even=1); v[1]=2; for(i=2, size, if(i%2==0, v[i]=gpf(odd+1); even*=v[i], v[i]=gpf(even+1); odd*=v[i])); v;

%Y Cf. A000946, A005266.

%K nonn

%O 1,1

%A _Anders Hellström_, Jul 15 2015

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Last modified January 20 16:38 EST 2019. Contains 319335 sequences. (Running on oeis4.)