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A178095 a(1)=a(2)=a(3)=1; thereafter a(n) = lpf(a(n-1)+a(n-2)+a(n-3)), where lpf = "least prime factor". 3

%I

%S 1,1,1,3,5,3,11,19,3,3,5,11,19,5,5,29,3,37,3,43,83,3,3,89,5,97,191,

%T 293,7,491,7,5,503,5,3,7,3,13,23,3,3,29,5,37,71,113,13,197,17,227,3,

%U 13,3,19,5,3,3,11,17,31,59,107,197,3,307,3,313,7,17,337,19,373,3,5,3,11,19,3,3,5,11,19,5,5,29,3,37,3,43,83,3,3,89,5,97,191,293,7,491,7

%N a(1)=a(2)=a(3)=1; thereafter a(n) = lpf(a(n-1)+a(n-2)+a(n-3)), where lpf = "least prime factor".

%C Has period 69, starting with the fourth term: 3, 5, 3, 11, 19, 3, 3, 5, 11, ...

%t nxt[{a_,b_,c_}]:={b,c,FactorInteger[a+b+c][[1,1]]}; Transpose[ NestList[ nxt,{1,1,1},100]][[1]] (* _Harvey P. Dale_, Aug 19 2014 *)

%Y Cf. A178094, A020639, A175723, A177904.

%K nonn

%O 1,4

%A _N. J. A. Sloane_, Dec 16 2010

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Last modified July 22 10:03 EDT 2019. Contains 325219 sequences. (Running on oeis4.)