login
This site is supported by donations to The OEIS Foundation.

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A050217 Super-Poulet numbers: Poulet numbers whose divisors d all satisfy d|2^d-2. 6
341, 1387, 2047, 2701, 3277, 4033, 4369, 4681, 5461, 7957, 8321, 10261, 13747, 14491, 15709, 18721, 19951, 23377, 31417, 31609, 31621, 35333, 42799, 49141, 49981, 60701, 60787, 65077, 65281, 80581, 83333, 85489, 88357, 90751 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Every semiprime in A001567 is in this sequence (see Sierpinski). a(61)=294409 is the first term having more than two prime factors. See A178997 for super-Poulet numbers having more than two prime factors. [T. D. Noe, Jan 11, 2011]

REFERENCES

W. Sierpinski, Elementary Theory of Numbers, Warszawa, 1964, p. 231.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Super-Poulet Numbers

Wikipedia, Super-Poulet number

MATHEMATICA

Select[Range[1, 110000, 2], !PrimeQ[#] && Union[PowerMod[2, Rest[Divisors[#]], #]] == {2} & ]

CROSSREFS

A214305 is a subsequence.

Cf. A001567.

Sequence in context: A083876 A068216 A038473 * A214305 A086837 A020230

Adjacent sequences:  A050214 A050215 A050216 * A050218 A050219 A050220

KEYWORD

nonn

AUTHOR

Eric W. Weisstein

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified July 29 11:04 EDT 2014. Contains 245021 sequences.