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A141747
a(n) is the number of nonnegative integer pairs i,j such that n = 2^i + 3^j.
2
0, 1, 1, 1, 2, 0, 1, 0, 1, 1, 2, 0, 1, 0, 0, 0, 2, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 2, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0
OFFSET
1,5
LINKS
FORMULA
G.f.: ( Sum_{i>=0} x^(2^i) ) * ( Sum_{j>=0} x^(3^j) ). - Ilya Gutkovskiy, Feb 10 2022
EXAMPLE
a(5) = 2, using (i,j) = (1,1) and (2,0).
MAPLE
f:= proc(n) local j, t, s;
t:= 0;
for j from 0 to floor(log[3](n)) do
s:= n - 3^j;
if s = 2^padic:-ordp(s, 2) then t:= t+1 fi
od;
t
end proc:
map(f, [$1..200]); # Robert Israel, Jun 08 2020
CROSSREFS
Sequence in context: A016242 A216659 A321396 * A239706 A328616 A260736
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jul 01 2008
STATUS
approved