2^[1,3]

["Ruud H.G. van Tol" <rvtol@isolution.nl>]

? 2^[1,3]
% [2.0000000000000000000000000000000000000, 
8.0000000000000000000000000000000000000]

? vecsum(2^[1,3])
% 10.000000000000000000000000000000000000

? vecsum([ 1<<e |e<-Set(digits(131)) ])
% 10


I wonder why 2^[1,3] uses reals.

- - - - -

How to best convert something like (int) 6131786 to (int) 2^1 + 2^3 + 
2^6 + 2^7 + 2^8?
(to be used as a Map-key)

-- Ruud

Example usage:

A096779_list(N) = {
  my(m(n)=vecsum([1<<e|e<-Set(digits(n))]), u=Map(), s=vector(2^10), 
v=vector(N));
  for(i=1, N
  , my(t=m(i), r=s[t]+1);
    while( bitand(t, m(r)) || mapisdefined(u, r), r++);
    mapput(~u, r, 0);
    s[t]=v[i]=r
  );
  v
}