
EXAMPLE

12 is 1100 in base 2, 110 in base 3 and 30 in base 4; in each representation every digit is smaller than or equal to the one proceeding so 12 is a term.
Similarly, 63 is 111111 in base 2, 2100 in base 3 and 333 in base 4 so it is also a term.


PROG

(PARI) dec(n, b)=my(v=digits(n, b)); v==vecsort(v, , 4)
is(n)=dec(n, 2) && dec(n, 3) && dec(n, 4) \\ Charles R Greathouse IV, May 03 2016
(PARI) dec(n, b)=my(v=digits(n, b)); v==vecsort(v, , 4)
list(lim)=my(v=List([0]), t); for(i=1, logint(lim\1+1, 4), t=4^i1; while(t<=lim, if(dec(t, 3), listput(v, t)); t*=4); t=2*4^i2; while(t<=lim, if(dec(t, 3), listput(v, t)); t*=4)); Set(v) \\ Charles R Greathouse IV, May 03 2016
