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A091178 Numbers k such that k-th prime is of the form 6*m+1. 15
4, 6, 8, 11, 12, 14, 18, 19, 21, 22, 25, 27, 29, 31, 34, 36, 37, 38, 42, 44, 46, 47, 48, 50, 53, 58, 59, 61, 63, 65, 67, 68, 70, 73, 74, 75, 78, 80, 82, 84, 85, 88, 90, 93, 95, 99, 100, 101, 105, 106, 110, 111, 112, 114, 115, 117, 121, 122, 125, 127, 129, 130 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A002476 indexed by A000040.
Also k for which prime(k) == 1 (mod 3). - Bruno Berselli, Mar 04 2016
Sequence A091177 (indices of primes of the form 3*k-1) is this sequence's complement in the positive integers without {2}. - M. F. Hasler, Sep 02 2016
The asymptotic density of this sequence is 1/2 (by Dirichlet's theorem). - Amiram Eldar, Feb 28 2021
LINKS
FORMULA
a(n) = k such that A000040(k) = A002476(n).
MATHEMATICA
Select[Range[200], IntegerQ[(Prime[#]-1)/6]&] (* Harvey P. Dale, Aug 25 2013 *)
PROG
(PARI) isok(n) = !((prime(n)-1) % 6); \\ Michel Marcus, Mar 04 2016
CROSSREFS
Cf. A000040, A002476 (primes of the form 6*m+1), A091177 (indices of primes of the form 3*k-1), A024892, A024899.
Sequence in context: A295287 A351758 A079254 * A270448 A152019 A091181
KEYWORD
nonn
AUTHOR
Ray Chandler, Dec 26 2003
EXTENSIONS
Definition edited by Zak Seidov, Oct 09 2014
STATUS
approved

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Last modified April 24 10:49 EDT 2024. Contains 371935 sequences. (Running on oeis4.)