VOOZH about

URL: https://oeis.org/A101795

⇱ A101795 - OEIS

login
A101795
Primes of the form 4*k-1 such that 8*k-1, 16*k-1 and 32*k-1 are also primes.
7
179, 359, 2699, 3539, 12119, 17159, 27479, 53639, 57839, 63419, 71399, 74699, 82499, 87539, 101399, 107279, 107699, 112919, 122099, 122819, 126839, 127139, 133499, 139439, 166739, 167759, 229739, 253679, 254279, 287219, 296099
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*A101794(n) - 1. - Amiram Eldar, May 13 2024
EXAMPLE
4*45-1 = 179, 8*45-1 = 359, 16*45-1 = 719 and 32*45-1 = 1439 are primes, so 179 is a term.
MATHEMATICA
Select[Table[4n-1, {n, 75000}], AllTrue[(#+1)*{1, 2, 4, 8}-1, PrimeQ]&] (* Harvey P. Dale, Apr 23 2019 *)
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) && isprime(32*m-1), 0); \\ Amiram Eldar, May 13 2024
CROSSREFS
Subsequence of A002145 and A101791.
Subsequence: A101995.
Sequence in context: A142670 A142948 A109985 * A142389 A063350 A094492
KEYWORD
easy,nonn
AUTHOR
Douglas Stones (dssto1(AT)student.monash.edu.au), Dec 16 2004
STATUS
approved