A071440 - OEIS

%I #5 Mar 30 2012 17:27:35

%S 1,2,6,42,26,48,92,96,132,20,6,42,26,48,92,96,132,20,6,42,26,48,92,96,

%T 132,20,6,42,26,48,92,96,132,20,6,42,26,48,92,96,132,20,6,42,26,48,92,

%U 96,132,20,6,42,26,48,92,96,132,20,6,42,26,48,92,96,132,20,6,42,26,48

%N Start with 1; add the digits of the previous term and the squares of the digits of the previous term.

%C The sequence becomes periodic after ten steps: a(10) = a(2). Period length is 8, length of the preperiodic part is 2. - Other starting values except 9, 90, 900, ... result in sequences which exhibit essentially the same behavior.

%e 42 -> 4 + 2 + 4^2 + 2^2 = 26, 26 -> 2 + 6 + 2^2 + 6^2 = 48, ...

%o (PARI) {m=70; a=1; for(j=1,m,print1(a,","); n=a; a=0; while(n>0,d=divrem(n,10); n=d[1]; a=a+(1+d[2])*d[2]))}

%K nonn,base,easy

%O 0,2

%A _N. J. A. Sloane_, Oct 23 2002

%E Edited and extended by _Klaus Brockhaus_, Oct 24 2002