Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A014234
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A014234 Largest prime <= 2^n. +0
12
2, 3, 7, 13, 31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, 32749, 65521, 131071, 262139, 524287, 1048573, 2097143, 4194301, 8388593, 16777213, 33554393, 67108859, 134217689, 268435399, 536870909, 1073741789 (list; graph; listen)
OFFSET

1,1

COMMENT

Whereas Harry J. Smith reports a total elapsed time of 10125.02 seconds, the Mathematica coding below on an Athlon 1.2GHz machine returns the same 32 terms in 0.01 seconds. - rgwv, Sep 02, 2002.

REFERENCES

D. E. Knuth, The Art of Computer Programming. Addison-Wesley, Reading, MA, Vol. 2, p. 390.

LINKS

Harry J. Smith, PrimePi2 - Computes the Prime Pi(x) counting function

MATHEMATICA

PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; Table[ Abs[ PrevPrim[2^n]], {n, 1, 30} ]

CROSSREFS

Cf. A000079.

Sequence in context: A048456 A071899 A102644 this_sequence A124430 A002013 A003120

Adjacent sequences: A014231 A014232 A014233 this_sequence A014235 A014236 A014237

KEYWORD

nonn

AUTHOR

Jud McCranie (j.mccranie(AT)comcast.net)

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