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A089888 Number of subsets of {1,.., n} containing at least one square. 2
1, 2, 4, 12, 24, 48, 96, 192, 448, 896, 1792, 3584, 7168, 14336, 28672, 61440, 122880, 245760, 491520, 983040, 1966080, 3932160, 7864320, 15728640, 32505856, 65011712, 130023424, 260046848, 520093696, 1040187392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = Sum(A089886(n,k): 1<=k<=A000196(n)) = A000079(n)-A089887(n) = A089887(n)*A000225(A000196(n)).

LINKS

Table of n, a(n) for n=1..30.

FORMULA

a(n) = (2^(n^(1/2))-n^(1/2))*2^(n-1).

CROSSREFS

Cf. A089890.

Sequence in context: A330592 A089822 A079352 * A291779 A181809 A181806

Adjacent sequences: A089885 A089886 A089887 * A089889 A089890 A089891

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 13 2003

STATUS

approved

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Last modified December 4 19:07 EST 2022. Contains 358563 sequences. (Running on oeis4.)