|
R:=proc(w) local k, x; x:=convert(w, base, 10);
add(x[nops(x)-k+1]*10^(k-1), k=1..nops(x)); end:
P:=proc(q) local a, k, n; for n from 2 to q do
a:=add(binomial(n-2*k, k), k=0..floor(n/3));
if a=R(a) then print(a); fi; od; end: P(10^5); # Paolo P. Lava, Nov 07 2017
# Alternatively:
a := proc(n) if n < 4 then n else
simplify(hypergeom([-n/3, (1-n)/3, (-1-n)/3], [-n/2, (-1-n)/2], -27/4));
convert(%, base, 10); ListTools:-Reverse(%);
if %% = % then add(%[k]*10^(k-1), k=1..nops(%)) else NULL fi fi end:
seq(a(n), n=1..200); # Peter Luschny, Nov 07 2017
| 