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".

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

Offset: 1

Author

N. J. A. Sloane, Dec 16 2010

Keywords

• nonn

Comments

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

Crossrefs

Cf. A178094, A020639, A175723, A177904.

Programs

Mathematica

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 *)