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A327736
Expansion of 1 / (1 - Sum_{i>=1, j>=0} x^(i*2^j)).
0
1, 1, 3, 6, 16, 35, 85, 195, 465, 1081, 2549, 5962, 14016, 32847, 77119, 180866, 424466, 995753, 2336497, 5481712, 12861904, 30176671, 70802913, 166120289, 389761751, 914476925, 2145596677, 5034105820, 11811287658, 27712248159, 65019931641, 152553127471, 357928110743
OFFSET
0,3
COMMENTS
Invert transform of A001511.
FORMULA
G.f.: 1 / (1 - Sum_{k>=0} x^(2^k) / (1 - x^(2^k))).
a(0) = 1; a(n) = Sum_{k=1..n} A001511(k) * a(n-k).
MATHEMATICA
nmax = 32; CoefficientList[Series[1/(1 - Sum[x^(2^k)/(1 - x^(2^k)), {k, 0, Floor[Log[2, nmax]] + 1}]), {x, 0, nmax}], x]
a[0] = 1; a[n_] := a[n] = Sum[IntegerExponent[2 k, 2] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 32}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Sep 23 2019
STATUS
approved