Cullen Number

Author

Eric W. Weisstein
April 19, 2010

This notebook downloaded from http://mathworld.wolfram.com/notebooks/IntegerSequences/CullenNumber.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/CullenNumber.html.

©2010 Wolfram Research, Inc. except for portions noted otherwise

Code

Cullen[n_]:=(2^n)n+1

Enumeration

Cullen/@Range[10]

Prime

Position[Cullen/@Range[1000],_?PrimeQ]//Flatten//Timing

A005849

Length[l={1,141,4713,5795,6611,18496,32292,32469,59656,90825,262419,361275,481899,1354828,6328548,6679881}]

Cullen/@Take[l,2]

IntegerLength/@Cullen/@l

Do[
Print[{i,l[[i]],PrimeQ[Cullen[l[[i]]]]//Timing}],
{i,Length[l]}
]

Do[
Print[{i,l[[i]],PrimeQ[Cullen[l[[i]]]]//Timing}],
{i,14,Length[l]}
]