A272638 a(1)=1, a(2)=4; thereafter a(n) = squarefree part of a(n-1)+a(n-2).

1, 4, 5, 1, 6, 7, 13, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7, 1, 2, 3, 5, 2, 7

Offset: 1

Author

N. J. A. Sloane, May 05 2016

Keywords

• nonn

Crossrefs

Rapidly merges with A272636.

Cf. A000045, A007913.

Programs

Maple

sqrf:= n-> mul(i[1]^irem(i[2], 2), i=ifactors(n)[2]):
f:=proc(n) global sqrf; option remember;
if n = 1 then 1 elif n=2 then 4 else sqrf(f(n-1)+f(n-2)); fi; end;
[seq(f(n),n=1..140)];