OFFSET
1,1
EXAMPLE
135 = 2^3*5. Square part of 135 is 9. Digit_sum(135) =9, digit_sum(9) = 9.
PROG
(PARI)
digsum(n)={local (d, p); d=0; p=n; while(p, d+=p%10; p=floor(p/10)); return(d)}
{for (n=2, 10^3, m=n/core(n); if(digsum(n)==digsum(m)&&m<>n, print(n))); }
CROSSREFS
KEYWORD
nonn,base,less
AUTHOR
Antonio Roldán, Oct 16 2013
STATUS
approved