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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A163079 Primes p such that p$ + 1 is also prime. Here '$' denotes the swinging factorial function (A056040). 4
2, 3, 5, 31, 67, 139, 631, 9743, 16253, 17977, 27901, 37589 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) are the primes in A163077.

REFERENCES

Peter Luschny, "Divide, swing and conquer the factorial and the lcm{1,2,...,n}", preprint, April 2008.

LINKS

Table of n, a(n) for n=1..12.

Peter Luschny, Swinging Primes.

EXAMPLE

5 is prime and 5$ + 1 = 30 + 1 = 31 is prime, so 5 is in the sequence.

MAPLE

a := proc(n) select(isprime, select(k -> isprime(A056040(k)+1), [$0..n])) end:

MATHEMATICA

f[n_] := 2^(n - Mod[n, 2])*Product[k^((-1)^(k + 1)), {k, n}]; p = 2; lst = {}; While[p < 38000, a = f@p + 1; If[ PrimeQ@a, AppendTo[ lst, p]; Print@p]; p = NextPrime@p]; lst (* Robert G. Wilson v, Aug 08 2010 *)

CROSSREFS

Cf. A163077, A062363, A093804, A002981.

Cf. A056040. - Robert G. Wilson v, Aug 09 2010

Sequence in context: A265807 A106308 A036797 * A109845 A241722 A276043

Adjacent sequences:  A163076 A163077 A163078 * A163080 A163081 A163082

KEYWORD

nonn,more

AUTHOR

Peter Luschny, Jul 21 2009

EXTENSIONS

a(8) - a(12) from Robert G. Wilson v, Aug 08 2010

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified March 29 07:35 EDT 2017. Contains 284250 sequences.