OFFSET
1,3
COMMENTS
If n=1 or 4, the row is extended until reaching 1 or 4 a second time after the starting value.
Conjecture: Each sequence terminates with 1 or the 4 16 37 58 89 145 42 20 4... loop.
REFERENCES
C. Stanley Ogilvy, Tomorrow's Math, 1972
EXAMPLE
The table starts in row 1 as
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;
5,25,29,85,89,145,42,20,4;
6,36,45,41,17,50,25,29,85,89,145,42,20,4;
PROG
(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; ) }
CROSSREFS
KEYWORD
easy,nonn,base,tabf
AUTHOR
Cino Hilliard, Apr 13 2003
EXTENSIONS
Redefined as an irregular table, merged 8 and 9 to 89 at one place - R. J. Mathar, Mar 14 2010
STATUS
approved