

A153347


Numbers n>0 such that 7*n4 is not prime.


1



2, 4, 6, 7, 8, 10, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 34, 36, 37, 38, 40, 42, 43, 44, 46, 47, 48, 49, 50, 52, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 76, 77, 78, 79, 80, 82, 84, 85, 86, 87, 88, 90, 91, 92
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OFFSET

1,1


LINKS

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


EXAMPLE

Distribution of the odd terms in the following triangular array:
*;
*,*;
*,*,*;
*,7,*,*;
*,*,*,*,*;
*,*,*,*,21,*;
7,*,*,*,*,*,*;
*,*,*,*,*,*,37,*;
*,*,*,25,*,*,*,*,*;
*,*,*,*,*,*,*,*,*,*;
*,17,*,*,*,*,*,*,63,*,*;
*,*,*,*,*,47,*,*,*,*,*,*;
*,*,*,*,43,*,*,*,*,*,*,97,*;
13,*,*,*,*,*,*,71,*,*,*,*,*,*; etc.
where * marks the noninteger values of (4*h*k + 2*k + 2*h + 5)/7 with h >= k >= 1.  Vincenzo Librandi, Jan 17 2013


MATHEMATICA

Select[Range[1, 200], !PrimeQ[7 #  4]&] (* Vincenzo Librandi, Jan 13 2013 *)


PROG

(Magma) [n: n in [1..150]  not IsPrime(7*n4)]; // Vincenzo Librandi, Jan 13 2013


CROSSREFS

Cf. A024903.
Sequence in context: A138204 A080645 A024413 * A330945 A153167 A227187
Adjacent sequences: A153344 A153345 A153346 * A153348 A153349 A153350


KEYWORD

nonn,easy


AUTHOR

Vincenzo Librandi, Dec 24 2008


EXTENSIONS

Erroneous comment deleted by N. J. A. Sloane, Jun 23 2010


STATUS

approved



