login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A101791 Primes of the form 4*k-1 such that 8*k-1 and 16*k-1 are also primes. 6
11, 179, 359, 719, 1019, 1031, 1451, 1511, 1811, 1931, 2459, 2699, 2819, 3491, 3539, 3911, 5399, 6131, 7079, 7151, 10691, 11171, 11471, 12119, 12899, 12959, 16811, 17159, 18191, 19319, 19991, 20411, 21011, 21179, 22271, 23099, 23819 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)
FORMULA
a(n) = 4*A101790(n) - 1. - Amiram Eldar, May 13 2024
EXAMPLE
4*3-1 = 11, 8*3-1 = 23 and 16*3-1 = 47 are primes, so 11 is a term.
MATHEMATICA
p4816Q[n_]:=Module[{nn=(n+1)/4}, And@@PrimeQ[{n, 8nn-1, 16nn-1}]]; Select[ 4*Range[6000]-1, p4816Q] (* Harvey P. Dale, Nov 25 2011 *)
PROG
(PARI) is(k) = if(k % 4 == 3, my(m = k\4 + 1); isprime(4*m-1) && isprime(8*m-1) && isprime(16*m-1), 0); \\ Amiram Eldar, May 13 2024
CROSSREFS
Subsequence of A002145.
Subsequences: A101795, A101995.
Sequence in context: A081740 A051687 A231916 * A140034 A363024 A162715
KEYWORD
easy,nonn
AUTHOR
Douglas Stones (dssto1(AT)student.monash.edu.au), Dec 16 2004
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 23 00:47 EDT 2024. Contains 373629 sequences. (Running on oeis4.)