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A089887
Number of subsets of {1,.., n} containing no squares.
4
1, 2, 4, 4, 8, 16, 32, 64, 64, 128, 256, 512, 1024, 2048, 4096, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456
OFFSET
1,2
COMMENTS
a(n) = Product(2-A010052(k): 1<=k<=n) = A089886(n,0) = A000079(n)-A089888(n).
FORMULA
a(n) = 2^(n-n^(1/2)).
PROG
(PARI) a(n)=2^(n-sqrtint(n)) \\ Charles R Greathouse IV, Apr 09 2012
CROSSREFS
Sequence in context: A321241 A290128 A291778 * A161816 A240347 A160124
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Nov 13 2003
STATUS
approved