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%I #5 Oct 01 2013 17:57:37
%S 1,1,2,4,3,9,81,65,61,37,58,89,145,42,20,4,4,16,37,58,89,145,42,20,4,
%T 5,25,29,85,89,145,42,20,4,6,36,45,41,17,50,25,29,85,89,145,42,20,4,7,
%U 49,97,130,10,1,8,64,52,29,85,89,145,42,20,4,9,81,65,61,37,58,89,145,42,20
%N Table which contains in row n the track of n->A003132(n) until reaching 1 or 4.
%C If n=1 or 4, the row is extended until reaching 1 or 4 a second time after the starting value.
%C Conjecture: Each sequence terminates with 1 or the 4 16 37 58 89 145 42 20 4... loop.
%D C. Stanley Ogilvy, Tomorrow's Math, 1972
%e The table starts in row 1 as
%e 1,1 ;
%e 2,4 ;
%e 3,9,81,65,61,37,58,89,145,42,20,4;
%e 4,16,37,58,89,145,42,20,4;
%e 5,25,29,85,89,145,42,20,4;
%e 6,36,45,41,17,50,25,29,85,89,145,42,20,4;
%o (PARI) \ The squared digital root of a number output initial terms digitsq2(m) = {y=0; for(x=1,m, digitsq(x) ) } digitsq(n) = { print1(n" "); while(1, s=0; while(n > 0, d=n%10; s = s+d*d; n=floor(n/10); ); print1(s" "); if(s==1 || s==4,break); n=s; ) }
%K easy,nonn,base,tabf
%O 1,3
%A _Cino Hilliard_, Apr 13 2003
%E Redefined as an irregular table, merged 8 and 9 to 89 at one place - _R. J. Mathar_, Mar 14 2010
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