Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A099442
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A099442 Semiprimes of the form A000295(n)=2^n-n-1. +0
4
4, 26, 57, 247, 502, 4083, 1073741793, 4294967263, 8589934558, 70368744177617, 4503599627370443, 4611686018427387841, 18889465931478580854709, 75557863725914323419059, 77371252455336267181195177 (list; graph; listen)
OFFSET

1,1

EXAMPLE

a(4)=247 because 247=13*19=2^8-8-1=2^A099441(4)-A099441(4)-1.

CROSSREFS

Cf. A000295 2^n-n-1 (column 2 of the Eulerian numbers), A099439 2^n-n-1 is prime, A099440 primes in A000295, A099441 2^n-n-1 is a semiprime.

Sequence in context: A059178 A056193 A102203 this_sequence A014450 A142962 A102198

Adjacent sequences: A099439 A099440 A099441 this_sequence A099443 A099444 A099445

KEYWORD

nonn

AUTHOR

Hugo Pfoertner (hugo(AT)pfoertner.org), Oct 18 2004

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


AT&T Labs Research