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A152921 2^(2p-1)/2, where p is A000043(n). 2
4, 16, 256, 4096, 16777216, 4294967296, 68719476736, 1152921504606846976 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Ultraperfect numbers (A139306), divided by 2.

Also, a(n) is the largest proper divisor of the n-th ultraperfect number.

LINKS

Table of n, a(n) for n=1..8.

FORMULA

a(n) = A139306(n)/2.

CROSSREFS

Cf. A000043, A139288, A139306, A152922, A152923.

Sequence in context: A200045 A099202 A139288 * A215116 A212297 A152153

Adjacent sequences:  A152918 A152919 A152920 * A152922 A152923 A152924

KEYWORD

nonn

AUTHOR

Omar E. Pol, Dec 15 2008

STATUS

approved

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Last modified June 24 21:16 EDT 2019. Contains 324337 sequences. (Running on oeis4.)