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!)
A132190 Numbers n such that 7*n^2 + 1 is prime. 1
2, 4, 8, 10, 12, 14, 18, 20, 22, 26, 30, 34, 44, 46, 58, 66, 68, 70, 74, 76, 78, 84, 90, 96, 100, 106, 108, 110, 120, 128, 134, 140, 146, 152, 154, 156, 158, 162, 164, 168, 174, 184, 186, 188, 196, 200, 202, 210, 216, 228, 232, 238, 250, 252, 260, 262, 264, 268 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

If n=2 then 7*n^2 + 1 = 29 (prime).

If n=100 then 7*n^2 + 1 = 70001 (prime).

MATHEMATICA

Select[Range[300], PrimeQ[7*#^2 + 1] &] (* Stefan Steinerberger, Jan 02 2008 *)

PROG

(Magma) [ n: n in [0..500] | IsPrime(7*n^2 + 1) ] // Vincenzo Librandi, Jan 31 2011

(PARI) is(n)=isprime(7*n^2+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A111051.

Sequence in context: A206928 A133012 A039011 * A155037 A001770 A032494

Adjacent sequences: A132187 A132188 A132189 * A132191 A132192 A132193

KEYWORD

nonn,easy

AUTHOR

Parthasarathy Nambi, Nov 05 2007

EXTENSIONS

More terms from Stefan Steinerberger, Jan 02 2008

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 January 26 22:13 EST 2023. Contains 359836 sequences. (Running on oeis4.)