A153384 - OEIS

A153384

Numbers n such that 24*n+1 is not prime.

0, 1, 2, 5, 6, 7, 9, 11, 12, 15, 16, 20, 21, 22, 23, 26, 27, 29, 30, 31, 33, 34, 35, 36, 37, 38, 40, 41, 44, 45, 46, 49, 51, 53, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 68, 70, 71, 72, 76, 77, 79, 80, 81, 82, 85, 86, 91, 92, 93, 94, 96, 97, 98, 100, 101, 102

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OFFSET

1,3

COMMENTS

Contains all numbers == 1 (mod 5), ==2 (mod 7), ==5 (mod 11), == 7 (mod 13), == 12 (mod 17), == 15 (mod 19), == 22 (mod 23), == 6 (mod 29) etc, so it is the union of A016861, A017005, A017449, A269044, etc. - R. J. Mathar, Jun 10 2020

Even terms of A153383, halved. - R. J. Mathar, Jun 10 2020

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

Triangle begins:

*,1;

*,*,2;

*,*,*,*;

*,*,*,*,5;

*,*,*,*,*,7;

*,*,*,*,*,*,*;

*,*,*,*,*,*,*,12;

*,*,*,*,*,*,*,*,15;

*,*,*,*,*,*,*,*,*,*;

*,*,*,*,*,*,*,*,*,*,22; etc.

where * marks the non-integer values of (2*h*k + k + h)/12 with h >= k >= 1. - Vincenzo Librandi, Jan 14 2013

MATHEMATICA

Select[Range[0, 200], !PrimeQ[24 # + 1] &] (* Vincenzo Librandi, Jan 14 2013 *)

PROG

(Magma) [n: n in [0..150] | not IsPrime(24*n + 1)]; // Vincenzo Librandi, Jan 14 2013

CROSSREFS

Cf. A001318, A111174 (complement).

Sequence in context: A161539 A177859 A047580 * A369962 A102657 A202115

Adjacent sequences: A153381 A153382 A153383 * A153385 A153386 A153387

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Dec 25 2008

EXTENSIONS

0 added by Arkadiusz Wesolowski, Aug 03 2011

STATUS

approved