OFFSET
0,6
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..8191
FORMULA
a(2^n-1) = A003121(n).
EXAMPLE
E.g. 201 = 11001001, so P(201) = {169, 197, 200}, a(201) = a(169) + a(197) + a(200).
MAPLE
P:= proc(n) local h, i, m, s, t;
t:= irem(n, 2, 'm');
s:= `if`(t=1, {n-1}, {});
for i from 0 while m>0 do h:= irem(m, 2, 'm');
if h=1 and t=0 then s:= s union {n- 2^i} fi; t:=h
od; s
end:
a:= proc(n) a(n):= `if`(n=0, 1, add(a(k), k=P(n))) end:
seq (a(n), n=0..80); # Alois P. Heinz, Jul 06 2012
MATHEMATICA
P[n_] := Module[{h, i, m, s, t}, {m, t} = QuotientRemainder[n, 2]; s = If[t == 1, {n-1}, {}]; For[i = 0, m>0, i++, {m, h} = QuotientRemainder[m, 2]; If[h == 1 && t == 0, s = s ~Union~ {n-2^i}]; t = h]; s]; a[n_] := a[n] = If[n == 0, 1, Sum[a[k], {k, P[n]}]]; Table[a[n], {n, 0, 80}] (* Jean-François Alcover, Jun 11 2015, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
David W. Wilson, Jan 29 2000
EXTENSIONS
Entry revised by N. J. A. Sloane, Jun 14 2012
STATUS
approved