A178179 Like A177904, but start with a(1)=0, a(2)=a(3)=1.

0, 1, 1, 2, 2, 5, 3, 5, 13, 7, 5, 5, 17, 3, 5, 5, 13, 23, 41, 11, 5, 19, 7, 31, 19, 19, 23, 61, 103, 17, 181, 43, 241, 31, 7, 31, 23, 61, 23, 107, 191, 107, 5, 101, 71, 59, 11, 47, 13, 71, 131, 43, 7, 181, 11, 199, 23, 233, 13, 269, 103, 11, 383, 71, 31, 97, 199, 109, 5, 313, 61, 379, 251, 691, 1321, 73, 139, 73, 19, 11, 103, 19, 19, 47, 17, 83, 7, 107, 197, 311, 41, 61, 59, 23, 13, 19, 11, 43, 73, 127, 3, 29, 53, 17, 11, 3, 31

Offset: 1

Author

N. J. A. Sloane, Dec 19 2010

Keywords

• nonn

Comments

After 7 steps, enters a cycle of length 100. The complete cycle, ending at 31, is shown.

Links

• Mihai Caragiu, Mathematical Trips.
• Greg Back and Mihai Caragiu, The Greatest Prime Factor and Recurrent Sequences, Fibonacci Quart. 48 (2010), no. 4, 358-362.

Crossrefs

Cf. A177904.

Programs

Mathematica

a[1] = 0; a[2] = a[3] = 1; a[n_] := a[n] = FactorInteger[a[n - 1] + a[n - 2] + a[n - 3]][[-1, 1]]; Array[a, 107] (* Robert G. Wilson v, Nov 17 2014 *)
nxt[{a_,b_,c_}]:={b,c,FactorInteger[a+b+c][[-1,1]]}; NestList[nxt,{0,1,1},110][[All,1]] (* Harvey P. Dale, Jul 17 2017 *)