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A213207
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Number of distinct products i*j*k over all triples (i,j,k) with |i| + |j| + |k| <= n.
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10
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1, 1, 1, 3, 5, 9, 13, 19, 25, 35, 43, 55, 65, 79, 91, 111, 127, 149, 167, 193, 217, 249, 273, 311, 339, 383, 419, 463, 501, 551, 591, 643, 693, 751, 799, 869, 925, 995, 1057, 1133, 1199, 1281, 1347, 1439, 1515, 1615, 1697, 1801, 1883, 2001, 2101, 2219, 2313
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OFFSET
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0,4
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COMMENTS
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This sequence is in reply to an extension request made in A100450.
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LINKS
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MAPLE
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h:= proc() true end:
b:= proc(n) local c, i, j, p;
c:=0;
for i to iquo(n, 3) do
for j from i to iquo(n-i, 2) do p:= i*j*(n-i-j);
if h(p) then h(p):= false; c:=c+1 fi
od
od; c
end:
a:= proc(n) a(n):= `if`(n=0, 1, a(n-1) +2*b(n)) end:
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MATHEMATICA
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f[n_] := Length[ Union[ Flatten[ Table[ If[ Abs[i] + Abs[j] + Abs[k] <= n, {i*j*k}, {0}], {i, -n, n}, {j, -n, n}, {k, -n, n}], 2]]]; Table[ f[n], {n, 0, 100}]
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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