login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A238900 Least k such that one of 2^n +- 2^k +- 1 is prime, where 0 < k < n, or 0 if there is no such prime. 2
1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 12, 2, 11, 1, 1, 1, 1, 2, 3, 9, 5, 2, 3, 3, 3, 4, 5, 4, 8, 3, 7, 4, 2, 6, 17, 14, 6, 12, 2, 5, 1, 2, 3, 6, 11, 5, 1, 16, 8, 8, 20, 2, 1, 5, 7, 19, 6, 4, 19, 8, 5, 4, 5, 3, 9, 6, 4, 3, 13, 1, 24 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,10

COMMENTS

Does a(n) = 0 for some n?

LINKS

T. D. Noe and Giovanni Resta, Table of n, a(n) for n = 2..10000 (first 1999 terms from T. D. Noe)

MATHEMATICA

Table[c1 = 2^n; k = 1; While[c2 = 2^k; k < n && ! (PrimeQ[c1 + c2 + 1] || PrimeQ[c1 + c2 - 1] || PrimeQ[c1 - c2 + 1] || PrimeQ[c1 - c2 - 1]), k++]; If[k == n, 0, k], {n, 2, 100}]

CROSSREFS

Cf. A196697.

Sequence in context: A091887 A144871 A066799 * A037832 A170977 A039737

Adjacent sequences:  A238897 A238898 A238899 * A238901 A238902 A238903

KEYWORD

nonn

AUTHOR

T. D. Noe, Mar 17 2014

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 20 07:16 EDT 2021. Contains 348099 sequences. (Running on oeis4.)