A056529 - OEIS

%I #3 Mar 30 2012 18:51:27

%S 0,3,1,2,2,1,1,2,0,1,3,1,0,1,1,0,3,1,2,3,1,1,1,2,1,3,2,3,1,1,1,2,2,1,

%T 2,2,3,1,1,2,1,2,2,3,1,2,1,1,2,2,1,1,3,2,2,1,2,1,1,1,1,3,3,3,1,2,2,1,

%U 2,1,2,2,3,2,2,2,2,2,1,2,2,3,2,2,1,2,3,2,3,1,3,2,3,2,1,2,2,3,2,1,3,1,1,1,1

%N Number of iterations of sum of digits of square to reach 1, 9, 13 or 16.

%e a(2)=3 because successive iterations give 2 -> 4 -> 7 -> 13 -> 16 -> 13 etc.

%Y Cf. A004159 for sum of digits of square, A056528 for two iterations, A056020 where iteration settles to 1, A056020 where iteration settles to 9, A056527 where iteration settles to 13 and 16.

%K base,easy,nonn

%O 1,2

%A _Henry Bottomley_, Jun 19 2000