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A134666 Number of multiply perfect numbers (A007691) having 2^n as the highest power of 2. 1
1, 1, 2, 2, 1, 4, 1, 5, 4, 4, 3, 6, 1, 3, 4, 5, 1, 9, 1, 19, 8, 9, 3, 5, 6, 7, 16, 13, 26, 20, 1, 6, 8, 6, 13, 23, 20, 6, 9, 33, 10, 11, 14, 18, 15, 13, 32, 23, 23, 18, 12, 20, 26, 21, 16, 17, 7, 11, 20, 15, 1, 10, 17, 14, 13, 26, 21, 16, 24, 13, 21, 27, 18, 14, 16, 21, 38, 19, 12, 26, 13, 23 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

It appears that a(n)>0 for all n. With the exception of n=2, a(n)=1 when n is p-1, where p is a Mersenne prime (A000043). Flammenkamp has an attractive graph of this sequence, including n for which there is incomplete data.

LINKS

Table of n, a(n) for n=0..81.

Achim Flammenkamp, The Multiply Perfect Numbers Page

EXAMPLE

a(2)=2 because only 28 and 2178540 have 2^2 as their highest power of 2.

CROSSREFS

Cf. A134665 (highest power of 2 for each MPN).

Sequence in context: A174714 A116633 A263232 * A129712 A051720 A022693

Adjacent sequences:  A134663 A134664 A134665 * A134667 A134668 A134669

KEYWORD

nonn

AUTHOR

T. D. Noe, Nov 05 2007

STATUS

approved

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Last modified November 14 00:05 EST 2019. Contains 329106 sequences. (Running on oeis4.)