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A080309 n-th even number equals n-th multiple of a Fermat number. 2
3, 5, 6, 9, 10, 12, 15, 17, 24, 25, 27, 30, 33, 34, 39, 40, 42, 45, 48, 50, 51, 60, 63, 65, 66, 68, 69, 70, 72, 75, 78, 80, 81, 95, 96, 111, 119, 120, 123, 125, 126, 129, 130, 132, 135, 136, 144, 159, 160, 174, 175, 177, 180, 183, 185, 186, 187, 189, 190, 192, 195, 204 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Sequence includes only multiples of Fermat numbers (sequence A080307), but not all of them. It is not certain that A080309 is infinite, but it seems likely given that exactly one-half of all integers are multiples of Fermat numbers (see A080307).

LINKS

Table of n, a(n) for n=1..62.

EXAMPLE

The first 3 even numbers are 2, 4 and 6; the first 3 multiples of Fermat numbers (the numbers of the form 2^(2^n)+1) are 3, 5 and 6. The third even number is also the third Fermat multiple; thus 3 is in the sequence.

CROSSREFS

Cf. A000215 (the Fermat numbers), A080307.

Sequence in context: A001969 A075311 A032786 * A281746 A287162 A018900

Adjacent sequences:  A080306 A080307 A080308 * A080310 A080311 A080312

KEYWORD

nonn

AUTHOR

Matthew Vandermast, Feb 16 2003

STATUS

approved

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Last modified December 10 16:44 EST 2018. Contains 318049 sequences. (Running on oeis4.)